diff --git a/CHANGELOG.md b/CHANGELOG.md
index a9dc65db..a5f86d1d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -41,6 +41,7 @@ any parts of the framework not mentioned in the documentation should generally b
     ```
 
 * `SerializerMethodResourceRelatedField(many=True)` relationship data now includes a meta section.
+* Required relationship fields are now marked as required in the OpenAPI schema.
 
 ### Fixed
 
diff --git a/example/tests/__snapshots__/test_openapi.ambr b/example/tests/__snapshots__/test_openapi.ambr
index fd270b40..93b8f7fb 100644
--- a/example/tests/__snapshots__/test_openapi.ambr
+++ b/example/tests/__snapshots__/test_openapi.ambr
@@ -587,6 +587,11 @@
                         "$ref": "#/components/schemas/reltoone"
                       }
                     },
+                    "required": [
+                      "bio",
+                      "entries",
+                      "comments"
+                    ],
                     "type": "object"
                   },
                   "type": {
@@ -801,6 +806,11 @@
                   "$ref": "#/components/schemas/reltoone"
                 }
               },
+              "required": [
+                "bio",
+                "entries",
+                "comments"
+              ],
               "type": "object"
             },
             "type": {
diff --git a/rest_framework_json_api/schemas/openapi.py b/rest_framework_json_api/schemas/openapi.py
index 4a0eeb83..a0d2be0d 100644
--- a/rest_framework_json_api/schemas/openapi.py
+++ b/rest_framework_json_api/schemas/openapi.py
@@ -631,6 +631,15 @@ def get_request_body(self, path, method):
             ):  # noqa E501
                 if "readOnly" in schema:
                     del item_schema["properties"]["attributes"]["properties"][name]
+
+        if "properties" in item_schema and "relationships" in item_schema["properties"]:
+            # No required relationships for PATCH
+            if (
+                method in ["PATCH", "PUT"]
+                and "required" in item_schema["properties"]["relationships"]
+            ):
+                del item_schema["properties"]["relationships"]["required"]
+
         return {
             "content": {
                 ct: {
@@ -653,6 +662,7 @@ def map_serializer(self, serializer):
         # TODO: remove attributes, etc. for relationshipView??
         required = []
         attributes = {}
+        relationships_required = []
         relationships = {}
 
         for field in serializer.fields.values():
@@ -668,11 +678,15 @@ def map_serializer(self, serializer):
                     ManySerializerMethodResourceRelatedField,
                 ),
             ):
+                if field.required:
+                    relationships_required.append(format_field_name(field.field_name))
                 relationships[format_field_name(field.field_name)] = {
                     "$ref": "#/components/schemas/reltomany"
                 }
                 continue
             if isinstance(field, serializers.RelatedField):
+                if field.required:
+                    relationships_required.append(format_field_name(field.field_name))
                 relationships[format_field_name(field.field_name)] = {
                     "$ref": "#/components/schemas/reltoone"
                 }
@@ -727,6 +741,10 @@ def map_serializer(self, serializer):
                 "type": "object",
                 "properties": relationships,
             }
+            if relationships_required:
+                result["properties"]["relationships"][
+                    "required"
+                ] = relationships_required
         return result
 
     def _add_async_response(self, operation):