diff --git a/src/main/java/org/codelibs/fess/mylasta/direction/FessConfig.java b/src/main/java/org/codelibs/fess/mylasta/direction/FessConfig.java
index bc007c00b..b8f84b022 100644
--- a/src/main/java/org/codelibs/fess/mylasta/direction/FessConfig.java
+++ b/src/main/java/org/codelibs/fess/mylasta/direction/FessConfig.java
@@ -426,6 +426,9 @@ public interface FessConfig extends FessEnv, org.codelibs.fess.mylasta.direction
     /** The key of the configuration. e.g. location */
     String QUERY_GEO_FIELDS = "query.geo.fields";
 
+    /** The key of the configuration. e.g. browser_lang */
+    String QUERY_BROWSER_LANG_PARAMETER_NAME = "query.browser.lang.parameter.name";
+
     /** The key of the configuration. e.g. true */
     String QUERY_REPLACE_TERM_WITH_PREFIX_QUERY = "query.replace.term.with.prefix.query";
 
@@ -2282,6 +2285,13 @@ public interface FessConfig extends FessEnv, org.codelibs.fess.mylasta.direction
      */
     String getQueryGeoFields();
 
+    /**
+     * Get the value for the key 'query.browser.lang.parameter.name'. <br>
+     * The value is, e.g. browser_lang <br>
+     * @return The value of found property. (NotNull: if not found, exception but basically no way)
+     */
+    String getQueryBrowserLangParameterName();
+
     /**
      * Get the value for the key 'query.replace.term.with.prefix.query'. <br>
      * The value is, e.g. true <br>
@@ -5044,6 +5054,10 @@ public interface FessConfig extends FessEnv, org.codelibs.fess.mylasta.direction
             return get(FessConfig.QUERY_GEO_FIELDS);
         }
 
+        public String getQueryBrowserLangParameterName() {
+            return get(FessConfig.QUERY_BROWSER_LANG_PARAMETER_NAME);
+        }
+
         public String getQueryReplaceTermWithPrefixQuery() {
             return get(FessConfig.QUERY_REPLACE_TERM_WITH_PREFIX_QUERY);
         }
diff --git a/src/main/java/org/codelibs/fess/mylasta/direction/sponsor/FessUserLocaleProcessProvider.java b/src/main/java/org/codelibs/fess/mylasta/direction/sponsor/FessUserLocaleProcessProvider.java
index 4fd30c260..730b1202f 100644
--- a/src/main/java/org/codelibs/fess/mylasta/direction/sponsor/FessUserLocaleProcessProvider.java
+++ b/src/main/java/org/codelibs/fess/mylasta/direction/sponsor/FessUserLocaleProcessProvider.java
@@ -17,17 +17,24 @@ package org.codelibs.fess.mylasta.direction.sponsor;
 
 import java.util.Locale;
 
+import org.apache.commons.lang3.LocaleUtils;
+import org.codelibs.core.lang.StringUtil;
+import org.codelibs.fess.mylasta.direction.FessConfig;
+import org.codelibs.fess.util.ComponentUtil;
 import org.dbflute.optional.OptionalObject;
 import org.dbflute.optional.OptionalThing;
 import org.dbflute.util.DfTypeUtil;
 import org.lastaflute.web.ruts.process.ActionRuntime;
 import org.lastaflute.web.servlet.request.RequestManager;
 import org.lastaflute.web.servlet.request.UserLocaleProcessProvider;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * @author jflute
  */
 public class FessUserLocaleProcessProvider implements UserLocaleProcessProvider {
+    private static final Logger logger = LoggerFactory.getLogger(FessUserLocaleProcessProvider.class);
 
     @Override
     public boolean isAcceptCookieLocale() {
@@ -36,7 +43,16 @@ public class FessUserLocaleProcessProvider implements UserLocaleProcessProvider
 
     @Override
     public OptionalThing<Locale> findBusinessLocale(final ActionRuntime runtimeMeta, final RequestManager requestManager) {
-        return OptionalObject.empty(); // to next determination
+        final FessConfig fessConfig = ComponentUtil.getFessConfig();
+        final String name = fessConfig.getQueryBrowserLangParameterName();
+        if (StringUtil.isNotBlank(name)) {
+            try {
+                return requestManager.getParameter(name).filter(StringUtil::isNotBlank).map(LocaleUtils::toLocale);
+            } catch (Exception e) {
+                logger.debug("Failed to parse a value of " + name + ".", e);
+            }
+        }
+        return OptionalObject.empty();
     }
 
     @Override
diff --git a/src/main/resources/fess_config.properties b/src/main/resources/fess_config.properties
index b90c2d333..37fcc60ee 100644
--- a/src/main/resources/fess_config.properties
+++ b/src/main/resources/fess_config.properties
@@ -202,6 +202,7 @@ index.indices.timeout=1m
 # query
 query.max.length=1000
 query.geo.fields=location
+query.browser.lang.parameter.name=browser_lang
 query.replace.term.with.prefix.query=true
 query.highlight.fragment.size=100
 query.max.search.result.offset=100000