Door positioning apparatus of door mounting device for vehicle

A door positioning apparatus of a door mounting device for a vehicle is disclosed. The disclosed door positioning apparatus of the door mounting device for a vehicle is configured to set a door in a re-mounting process of a designing factory, to construct the door in the door mounting device to move the door to a position of where the door is mounted, and to position the door which is set in the door mounting device at the fixed position. The present invention may comprise i) a mounting frame mounted to be reciprocally movable along the movement direction of the door at a base frame of the door mounting device; and ii) a pair of reference pins installed to be reciprocally movable in the end portion of the vehicle body side of the mounting frame in the vertical direction, and to set a reference position of the door for a pair of door hinges mounted on the vehicle body.