diff --git a/moto/sns/models.py b/moto/sns/models.py
index 26125b90c..7d4ff85d1 100644
--- a/moto/sns/models.py
+++ b/moto/sns/models.py
@@ -662,6 +662,9 @@ class SNSBackend(BaseBackend):
 
     def delete_platform_application(self, platform_arn):
         self.applications.pop(platform_arn)
+        endpoints = self.list_endpoints_by_platform_application(platform_arn)
+        for endpoint in endpoints:
+            self.platform_endpoints.pop(endpoint.arn)
 
     def create_platform_endpoint(
         self, region, application, custom_user_data, token, attributes
diff --git a/tests/test_sns/test_application_boto3.py b/tests/test_sns/test_application_boto3.py
index 8c31f217d..4489ccfed 100644
--- a/tests/test_sns/test_application_boto3.py
+++ b/tests/test_sns/test_application_boto3.py
@@ -375,3 +375,26 @@ def test_get_sms_attributes_filtered():
     response["attributes"].should.contain("DefaultSMSType")
     response["attributes"].should_not.contain("test")
     response["attributes"]["DefaultSMSType"].should.equal("Transactional")
+
+
+@mock_sns
+def test_delete_endpoints_of_delete_app():
+    conn = boto3.client("sns", region_name="us-east-1")
+
+    platform_app_arn = conn.create_platform_application(
+        Name="app-test-kevs", Platform="GCM", Attributes={"PlatformCredential": "test"}
+    )["PlatformApplicationArn"]
+
+    endpoint_arn = conn.create_platform_endpoint(
+        PlatformApplicationArn=platform_app_arn,
+        Token="test",
+    )["EndpointArn"]
+
+    conn.delete_platform_application(PlatformApplicationArn=platform_app_arn)
+
+    with pytest.raises(conn.exceptions.NotFoundException) as excinfo:
+        conn.get_endpoint_attributes(EndpointArn=endpoint_arn)
+    error = excinfo.value.response["Error"]
+    error["Type"].should.equal("Sender")
+    error["Code"].should.equal("NotFound")
+    error["Message"].should.equal("Endpoint does not exist")