PURPOSE: To readily and rapidly fix a loading space unit to a mobile car body by making the height of a coupling part of the mobile car body from the ground higher than that of a coupling unit of a stand of the loading space unit in a standing state.

CONSTITUTION: A loading space unit 1 is supported by a stand 2 and rotary wheels 3 and the rotary wheels 3 are locked by moving a supporting frame 10 backwards and actuating a brake unit 11 thereby. A mobile car body 4 is moved backwards and a coupling part 6 of the loading space unit 1 is introduced to a coupling unit 5 thereof. A locking member 13 is pushed downwards for coupling at the normal position and the supporting frame 10 is rotated to the front for taking off the brake unit 11. The loading space unit becomes to a state in which goods can be loaded thereby.