PURPOSE: To prevent the hanging down of the central part of a sheeted blank member under its own weight as it is softened by heating by a method in which the sheeted blank member is attracted by the downside of a heating board and heated by the conductional heat of the heating board.

CONSTITUTION: A heating board 4 having an electrical heater A is set on the upper part of a material feeding path in such a state that the downside 4a of the board 4 closely comes near a sheeted blank member 1. The heating board 4 has many small holes 3 in the whole surface, which are connected to the suction port and discharge port of an air pump through an electromagnetic switch valve and a pipe. In this system, a condition that suction force is acted through the small holes 3 and a condition that air is blown out and acted through the small holes 3 can be switched to each other by operating a switching valve.