diff --git a/src/main/java/org/codelibs/fess/helper/QueryHelper.java b/src/main/java/org/codelibs/fess/helper/QueryHelper.java
index 271cea2b8..d580b054e 100644
--- a/src/main/java/org/codelibs/fess/helper/QueryHelper.java
+++ b/src/main/java/org/codelibs/fess/helper/QueryHelper.java
@@ -295,10 +295,10 @@ public class QueryHelper implements Serializable {
                     boolQuery.must(queryBuilder);
                     break;
                 case SHOULD:
-                    boolQuery.must(queryBuilder);
+                    boolQuery.should(queryBuilder);
                     break;
                 case MUST_NOT:
-                    boolQuery.must(queryBuilder);
+                    boolQuery.mustNot(queryBuilder);
                     break;
                 default:
                     break;
diff --git a/src/main/resources/app.xml b/src/main/resources/app.xml
index 6605c455e..ccb113bfd 100644
--- a/src/main/resources/app.xml
+++ b/src/main/resources/app.xml
@@ -26,6 +26,7 @@
 			<component class="org.apache.lucene.analysis.core.WhitespaceAnalyzer"></component>
 		</arg>
 		<property name="lowercaseExpandedTerms">false</property>
+		<property name="defaultOperator">org.apache.lucene.queryparser.classic.QueryParser$Operator.AND</property>
 	</component>
 	<component name="queryHelper" class="org.codelibs.fess.helper.QueryHelper">
 		<property name="defaultFacetInfo">