PURPOSE: To facilitate a re-stacking job and to prevent stacked cargoes from falling down by freely setting the rear end of a upper link either to a position parallel to a lower link or to a position satisfying a relation where said rear end gradually separates from said lower link as it goes backward.

CONSTITUTION: If the rear end of a upper link 9 is engaged with an engaging part 33 on the lower side of a mast frame 25, and a lower link 5 is lifted by a lift arm 7 and a rod 8 keeping said state, a mast frame 25 can be lifted while being kept in vertical attitude, since the lower link 5 and a upper link 9 satisfy the link mechanism relation of a parallelogram. When the ground 32 is uneven, the rear end of the upper link 9 should be engaged with an engaging part 34. Then, the stacked cargoes will not fall down since a lift 37 is inclined forwardly.