diff --git a/src/main/kotlin/com/tfandkusu/ga913yaml/Main.kt b/src/main/kotlin/com/tfandkusu/ga913yaml/Main.kt
index 5dcc950..ab8d8ff 100644
--- a/src/main/kotlin/com/tfandkusu/ga913yaml/Main.kt
+++ b/src/main/kotlin/com/tfandkusu/ga913yaml/Main.kt
@@ -9,7 +9,8 @@ fun main(args: Array<String>) {
     val command = args[0]
     when (command) {
         "validate" -> {
-            YamlParser.parse()
+            val screens = YamlParser.parse()
+            Validator.validate(screens)
         }
         "make" -> {
             val screens = YamlParser.parse()
diff --git a/src/main/kotlin/com/tfandkusu/ga913yaml/Validator.kt b/src/main/kotlin/com/tfandkusu/ga913yaml/Validator.kt
new file mode 100644
index 0000000..a49aefe
--- /dev/null
+++ b/src/main/kotlin/com/tfandkusu/ga913yaml/Validator.kt
@@ -0,0 +1,75 @@
+package com.tfandkusu.ga913yaml
+
+import com.tfandkusu.ga913yaml.model.Screen
+
+object Validator {
+    fun validate(screens: List<Screen>) {
+        checkEventNameLength(screens)
+        checkEventParameterKeyLength(screens)
+        checkEventCount(screens)
+        checkDuplicateEventName(screens)
+    }
+
+    /**
+     * イベント名の長さが40文字を超えていないかチェックする。
+     */
+    private fun checkEventNameLength(screens: List<Screen>) {
+        for (screen in screens) {
+            if (screen.eventName.length > 40) {
+                throw IllegalArgumentException("画面遷移イベント " + screen.className + " は40文字を超えています。")
+            }
+            for (action in screen.actions) {
+                if (screen.eventName.length + action.eventName.length > 40) {
+                    throw IllegalArgumentException(
+                        "画面内操作イベント " + screen.className + "." + action.className + " は40文字を超えています。",
+                    )
+                }
+            }
+        }
+    }
+
+    /**
+     * イベントパラメータキーの長さが40文字を超えていないかチェックする。
+     */
+    private fun checkEventParameterKeyLength(screens: List<Screen>) {
+        for (screen in screens) {
+            for (action in screen.actions) {
+                for (parameter in action.parameters) {
+                    if (parameter.eventParameterKey.length > 40) {
+                        throw IllegalArgumentException(
+                            "画面内操作イベント " + screen.className + "." + action.className + " のパラメータキー " +
+                                parameter.propertyName + " は40文字を超えています。",
+                        )
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * イベント種類数が500を超えていないかチェックする。
+     */
+    private fun checkEventCount(screens: List<Screen>) {
+        val eventCount =
+            screens.count { it.isConversionEvent } + screens.flatMap { it.actions }.count { it.isConversionEvent }
+        if (eventCount > 500) {
+            throw IllegalArgumentException("イベント種類数が500を超えています。")
+        }
+    }
+
+    private fun checkDuplicateEventName(screens: List<Screen>) {
+        val eventNames = mutableSetOf<String>()
+        for (screen in screens) {
+            if (!eventNames.add(screen.eventName)) {
+                throw IllegalArgumentException("画面遷移イベント " + screen.className + " は他のイベントと重複しています。")
+            }
+            for (action in screen.actions) {
+                if (!eventNames.add(screen.eventName + action.eventName)) {
+                    throw IllegalArgumentException(
+                        "画面内操作イベント " + screen.className + "." + action.className + " は他のイベントと重複しています。",
+                    )
+                }
+            }
+        }
+    }
+}
diff --git a/src/test/kotlin/com/tfandkusu/ga913yaml/ValidatorTest.kt b/src/test/kotlin/com/tfandkusu/ga913yaml/ValidatorTest.kt
new file mode 100644
index 0000000..956d8f5
--- /dev/null
+++ b/src/test/kotlin/com/tfandkusu/ga913yaml/ValidatorTest.kt
@@ -0,0 +1,254 @@
+package com.tfandkusu.ga913yaml
+
+import com.tfandkusu.ga913yaml.model.Action
+import com.tfandkusu.ga913yaml.model.Parameter
+import com.tfandkusu.ga913yaml.model.ParameterType
+import com.tfandkusu.ga913yaml.model.Screen
+import org.junit.Assert.assertEquals
+import org.junit.Assert.fail
+import org.junit.Test
+
+class ValidatorTest {
+    @Test
+    fun checkScreenEventNameLength() {
+        val screens =
+            listOf(
+                Screen(
+                    description = "40文字を超えない画面遷移イベント",
+                    className = "Screen1",
+                    eventName = "a".repeat(40),
+                ),
+                Screen(
+                    description = "40文字を超える画面遷移イベント",
+                    className = "Screen2",
+                    eventName = "b".repeat(41),
+                ),
+            )
+        try {
+            Validator.validate(screens)
+            fail()
+        } catch (e: IllegalArgumentException) {
+            assertEquals("画面遷移イベント Screen2 は40文字を超えています。", e.message)
+        }
+    }
+
+    @Test
+    fun checkActionEventNameLength() {
+        val screens =
+            listOf(
+                Screen(
+                    description = "画面1",
+                    className = "Screen1",
+                    eventName = "a".repeat(20),
+                    actions =
+                        listOf(
+                            Action(
+                                description = "40文字を超えない画面内操作イベント",
+                                className = "Action1",
+                                eventName = "b".repeat(20),
+                            ),
+                            Action(
+                                description = "40文字を超える画面内操作イベント",
+                                className = "Action2",
+                                eventName = "c".repeat(21),
+                            ),
+                        ),
+                ),
+            )
+        try {
+            Validator.validate(screens)
+            fail()
+        } catch (e: IllegalArgumentException) {
+            assertEquals(
+                "画面内操作イベント Screen1.Action2 は40文字を超えています。",
+                e.message,
+            )
+        }
+    }
+
+    @Test
+    fun checkEventParameterKeyLength() {
+        val screens =
+            listOf(
+                Screen(
+                    description = "画面1",
+                    className = "Screen1",
+                    eventName = "Scene1",
+                    actions =
+                        listOf(
+                            Action(
+                                description = "画面内操作1",
+                                className = "Action1",
+                                eventName = "Action1",
+                                parameters =
+                                    listOf(
+                                        Parameter(
+                                            description = "40文字を超えないパラメータキー",
+                                            propertyName = "param1",
+                                            eventParameterKey = "a".repeat(40),
+                                            type = ParameterType.STRING,
+                                        ),
+                                        Parameter(
+                                            description = "40文字を超えるパラメータキー",
+                                            propertyName = "param2",
+                                            eventParameterKey = "b".repeat(41),
+                                            type = ParameterType.STRING,
+                                        ),
+                                    ),
+                            ),
+                        ),
+                ),
+            )
+        try {
+            Validator.validate(screens)
+            fail()
+        } catch (e: IllegalArgumentException) {
+            assertEquals(
+                "画面内操作イベント Screen1.Action1 のパラメータキー param2 は40文字を超えています。",
+                e.message,
+            )
+        }
+    }
+
+    @Test
+    fun checkEventCountWithoutException() {
+        val screens =
+            (0 until 250).map {
+                Screen(
+                    description = "画面$it",
+                    className = "Screen$it",
+                    eventName = "Scene$it",
+                    actions =
+                        listOf(
+                            Action(
+                                description = "画面内操作1",
+                                className = "Action1",
+                                eventName = "Action1",
+                                isConversionEvent = true,
+                            ),
+                        ),
+                    isConversionEvent = true,
+                )
+            }
+        Validator.validate(screens)
+    }
+
+    @Test
+    fun checkEventCountWithException() {
+        val screens =
+            (0 until 250).map {
+                Screen(
+                    description = "画面$it",
+                    className = "Screen$it",
+                    eventName = "Scene$it",
+                    actions =
+                        listOf(
+                            Action(
+                                description = "画面内操作1",
+                                className = "Action1",
+                                eventName = "Action1",
+                                isConversionEvent = true,
+                            ),
+                        ),
+                    isConversionEvent = true,
+                )
+            } +
+                Screen(
+                    description = "画面250",
+                    className = "Screen250",
+                    eventName = "Scene250",
+                    isConversionEvent = true,
+                )
+        try {
+            Validator.validate(screens)
+            fail()
+        } catch (e: IllegalArgumentException) {
+            assertEquals("イベント種類数が500を超えています。", e.message)
+        }
+    }
+
+    @Test
+    fun checkScreenEventNameDuplicate() {
+        val screens =
+            listOf(
+                Screen(
+                    description = "画面1",
+                    className = "Screen1",
+                    eventName = "Screen1",
+                ),
+                Screen(
+                    description = "画面2",
+                    className = "Screen2",
+                    eventName = "Screen1",
+                ),
+            )
+        try {
+            Validator.validate(screens)
+            fail()
+        } catch (e: IllegalArgumentException) {
+            assertEquals("画面遷移イベント Screen2 は他のイベントと重複しています。", e.message)
+        }
+    }
+
+    @Test
+    fun checkActionEventNameDuplicate() {
+        val screens =
+            listOf(
+                Screen(
+                    description = "画面1",
+                    className = "Screen1",
+                    eventName = "Screen1",
+                    actions =
+                        listOf(
+                            Action(
+                                description = "画面内操作1",
+                                className = "Action1",
+                                eventName = "Action1",
+                            ),
+                            Action(
+                                description = "画面内操作2",
+                                className = "Action2",
+                                eventName = "Action1",
+                            ),
+                        ),
+                ),
+            )
+        try {
+            Validator.validate(screens)
+            fail()
+        } catch (e: IllegalArgumentException) {
+            assertEquals("画面内操作イベント Screen1.Action2 は他のイベントと重複しています。", e.message)
+        }
+    }
+
+    @Test
+    fun checkJoinedEventNameDuplicate() {
+        val screens =
+            listOf(
+                Screen(
+                    description = "画面1",
+                    className = "Screen1",
+                    eventName = "Screen1",
+                    actions =
+                        listOf(
+                            Action(
+                                description = "画面内操作1",
+                                className = "Action1",
+                                eventName = "Action1",
+                            ),
+                        ),
+                ),
+                Screen(
+                    description = "画面2",
+                    className = "Screen2",
+                    eventName = "Screen1Action1",
+                ),
+            )
+        try {
+            Validator.validate(screens)
+            fail()
+        } catch (e: IllegalArgumentException) {
+            assertEquals("画面遷移イベント Screen2 は他のイベントと重複しています。", e.message)
+        }
+    }
+}