A rear door is supported at a rear end of a vehicle by a hinge assembly, which includes a hinge base part and a door hinge part. The hinge base part is provided in a groove formed at a joint between a roof panel and a side panel of a vehicle body, and the door hinge part is attached to the rear door and swingably supported by the hinge base part. The hinge base part includes an anchor portion fixed to a bottom of the groove, a swing motion support portion disposed in a position aligned in a longitudinal direction of the vehicle with the anchor portion and separate from the anchor portion to support the door hinge part, and a connecting portion extending between the anchor portion and the swing motion support portion to fix the swing motion support portion relative to the anchor portion.