PURPOSE: To eliminate a different elevating device, to improve working efficiency, and to decrease thickness by arranging a conveyance substance lifting mechanism to elevate a conveyance substance-loading pallet through expansion and contraction of an air bag to a bed 1 having an air bearing.

CONSTITUTION: A conveyance substance-loading pallet 2 is freely elevated by means of conveyance substance lifting mechanism parts 8 on both sides of a bed 1 and an air bearing 3 is located under gangway foot plates 6 located to the four corners of the bed 1. The bed 1 for a conveying device is inserted in a gap in the under surface of a conveyance substance and the loading pallet 2 is raised. In this case, lower and upper air bags 11a and 11b, are expanded by means of air from a control valve through an air introduction pipe 12. A plate 92 for an air bag is raised and resultantly a leg part 2a of the loading pallet 2 is first guided by a guide 21, and subsequently the guide 21 is guided to a side 7a of a base plate 7 for raising to push up an under surface 17 of the conveyance substance by means of the loading panel 2. In this case, the presence of the guide 21 causes prevention of lateral swing of the loading panel 2.