diff --git a/package/samplers/ctpe/README.md b/package/samplers/ctpe/README.md
index 3dfd215d..6cadf7af 100644
--- a/package/samplers/ctpe/README.md
+++ b/package/samplers/ctpe/README.md
@@ -1,7 +1,7 @@
 ---
 author: Shuhei Watanabe
-title: "c-TPE: Tree-structured Parzen Estimator with Inequality Constraints for Expensive Hyperparameter Optimization"
-description: "The optimizer that reproduces the algorithm described in the paper `c-TPE: Tree-structured Parzen Estimator with Inequality Constraints for Expensive Hyperparameter Optimization`".
+title: 'c-TPE: Tree-structured Parzen Estimator with Inequality Constraints for Expensive Hyperparameter Optimization'
+description: 'The optimizer that reproduces the algorithm described in the paper `c-TPE: Tree-structured Parzen Estimator with Inequality Constraints for Expensive Hyperparameter Optimization`.'
 tags: [sampler, tpe, c-tpe, paper, research]
 optuna_versions: [v4.1.0]
 license: MIT License