diff --git a/src/caret_analyze/plot/stacked_bar/latency_stacked_bar.py b/src/caret_analyze/plot/stacked_bar/latency_stacked_bar.py
index ffc76e0aa..1515f48e7 100644
--- a/src/caret_analyze/plot/stacked_bar/latency_stacked_bar.py
+++ b/src/caret_analyze/plot/stacked_bar/latency_stacked_bar.py
@@ -51,9 +51,6 @@ def to_dataframe(
             Latency dataframe.
 
         """
-        converter: ClockConverter | None = None
-        if xaxis_type == 'sim_time':
-            converter = get_clock_converter([self._target_objects])
         # NOTE: returned columns aren't used because they don't include 'start time'
         # TODO: delete 1e-6
         stacked_bar_dict, _ = self.to_stacked_bar_data(xaxis_type)
diff --git a/src/caret_analyze/plot/visualize_lib/bokeh/stacked_bar.py b/src/caret_analyze/plot/visualize_lib/bokeh/stacked_bar.py
index f38ff39ac..1f9554a5a 100644
--- a/src/caret_analyze/plot/visualize_lib/bokeh/stacked_bar.py
+++ b/src/caret_analyze/plot/visualize_lib/bokeh/stacked_bar.py
@@ -20,8 +20,6 @@
 
 from .util import (apply_x_axis_offset, ColorSelectorFactory,
                    HoverKeysFactory, init_figure)
-from ...util import get_clock_converter
-from ....common import ClockConverter
 
 
 class BokehStackedBar:
@@ -75,7 +73,7 @@ def create_figure(self) -> Figure:
         x_label = 'start time'
         if self._xaxis_type == 'system_time' or self._xaxis_type == 'sim_time':
             apply_x_axis_offset(fig, frame_min, frame_max)
-        else: # index
+        else:  # index
             x_label = 'index'
 
         color_selector = ColorSelectorFactory.create_instance(coloring_rule='unique')
diff --git a/src/caret_analyze/record/records_service/stacked_bar.py b/src/caret_analyze/record/records_service/stacked_bar.py
index c92a3beb1..5c5d2c897 100644
--- a/src/caret_analyze/record/records_service/stacked_bar.py
+++ b/src/caret_analyze/record/records_service/stacked_bar.py
@@ -64,7 +64,7 @@ def __init__(
         stacked_bar_records = self._to_stacked_bar_records(renamed_records, columns)
         series_seq: Sequence[int | None] = x_axis_values.get_column_series(xlabel)
         if converter:
-            series_seq = [round(converter.convert(t)) for t in series_seq]
+            series_seq = [round(converter.convert(float(t))) for t in series_seq if t is not None]
         series_list: list[int] = self._convert_sequence_to_list(series_seq)
         stacked_bar_records = \
             self._merge_column_series(