diff --git a/pyproject.toml b/pyproject.toml
index 3edd658..9b9c82c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,7 +27,7 @@ dependencies = [
 
 [project.optional-dependencies]
 dev = [
-  "build>=1.2.2,<1.6.0",
+  "build>=1.2.2,<1.7.0",
   "ruff>=0.12.2,<0.17.0",
   "mkdocs>=1.6,<2.0",
   "mkdocs-material>=9.5,<10.0",
@@ -48,7 +48,7 @@ homepage = "https://github.com/CyberAgentAILab/python-dte-adjustment"
 
 [tool.uv]
 dev-dependencies = [
-  "build>=1.2.2,<1.6.0",
+  "build>=1.2.2,<1.7.0",
   "build>=1.2.2,<1.4.0",
   "ruff>=0.12.2,<0.17.0",
   "mkdocs>=1.6,<2.0",