diff --git a/apis/flinkcluster/v1beta1/flinkcluster_default.go b/apis/flinkcluster/v1beta1/flinkcluster_default.go
index 6834e2fa..e2ae463e 100644
--- a/apis/flinkcluster/v1beta1/flinkcluster_default.go
+++ b/apis/flinkcluster/v1beta1/flinkcluster_default.go
@@ -27,6 +27,7 @@ import (
 )
 
 const (
+	DefaultParallelism         = -1
 	DefaultJobManagerReplicas  = 1
 	DefaultTaskManagerReplicas = 3
 	ForceTearDownAfter         = time.Second * 10
diff --git a/apis/flinkcluster/v1beta1/flinkcluster_validate.go b/apis/flinkcluster/v1beta1/flinkcluster_validate.go
index cac603a1..5f962e02 100644
--- a/apis/flinkcluster/v1beta1/flinkcluster_validate.go
+++ b/apis/flinkcluster/v1beta1/flinkcluster_validate.go
@@ -533,8 +533,8 @@ func (v *Validator) validateJob(jobSpec *JobSpec) error {
 		return fmt.Errorf("job jarFile or pythonFile or pythonModule is unspecified")
 	}
 
-	if jobSpec.Parallelism != nil && *jobSpec.Parallelism < 1 {
-		return fmt.Errorf("job parallelism must be >= 1")
+	if jobSpec.Parallelism != nil && *jobSpec.Parallelism < 1 && *jobSpec.Parallelism != DefaultParallelism {
+		return fmt.Errorf("job parallelism must be -1 (adaptive) or >= 1")
 	}
 
 	if jobSpec.RestartPolicy == nil {