diff --git a/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java b/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java
index 55333e313..b364d44e0 100644
--- a/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java
+++ b/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java
@@ -82,9 +82,9 @@ public class DataConfig extends BsDataConfig implements CrawlingConfig {
 
     private Map<String, String> handlerScriptMap;
 
-    private List<LabelType> labelTypeList;
+    private volatile List<LabelType> labelTypeList;
 
-    private List<RoleType> roleTypeList;
+    private volatile List<RoleType> roleTypeList;
 
     public DataConfig() {
         super();
diff --git a/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java b/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java
index 1bb0bed5e..374d32f81 100644
--- a/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java
+++ b/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java
@@ -57,9 +57,9 @@ public class FileConfig extends BsFileConfig implements CrawlingConfig {
 
     protected volatile Map<ConfigName, Map<String, String>> configParameterMap;
 
-    private List<LabelType> labelTypeList;
+    private volatile List<LabelType> labelTypeList;
 
-    private List<RoleType> roleTypeList;
+    private volatile List<RoleType> roleTypeList;
 
     public FileConfig() {
         super();
diff --git a/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java b/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java
index ddb941e08..abe0e6a00 100644
--- a/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java
+++ b/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java
@@ -57,9 +57,9 @@ public class WebConfig extends BsWebConfig implements CrawlingConfig {
 
     protected volatile Map<ConfigName, Map<String, String>> configParameterMap;
 
-    private List<LabelType> labelTypeList;
+    private volatile List<LabelType> labelTypeList;
 
-    private List<RoleType> roleTypeList;
+    private volatile List<RoleType> roleTypeList;
 
     public WebConfig() {
         super();