diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
index 39709529c00d..0a6737ba4211 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
@@ -373,6 +373,9 @@ object BooleanSimplification extends Rule[LogicalPlan] with PredicateHelper {
       case Not(a And b) => Or(Not(a), Not(b))
 
       case Not(Not(e)) => e
+
+      case Not(IsNull(e)) => IsNotNull(e)
+      case Not(IsNotNull(e)) => IsNull(e)
     }
   }
 }
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/BooleanSimplificationSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/BooleanSimplificationSuite.scala
index a0de5f693095..a8b8417754b0 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/BooleanSimplificationSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/BooleanSimplificationSuite.scala
@@ -239,6 +239,11 @@ class BooleanSimplificationSuite extends PlanTest with ExpressionEvalHelper with
     checkCondition(!'f || 'e, testRelationWithData.where(!'f || 'e).analyze)
   }
 
+  test("simplify NOT(IsNull(x)) and NOT(IsNotNull(x))") {
+    checkCondition(Not(IsNotNull('b)), IsNull('b))
+    checkCondition(Not(IsNull('b)), IsNotNull('b))
+  }
+
   protected def assertEquivalent(e1: Expression, e2: Expression): Unit = {
     val correctAnswer = Project(Alias(e2, "out")() :: Nil, OneRowRelation()).analyze
     val actual = Optimize.execute(Project(Alias(e1, "out")() :: Nil, OneRowRelation()).analyze)