Abstract: An apparatus for heating a printed circuit board includes a conveyor (2) to transport a printed circuit board (1), and a heating chamber (3) through which the printed circuit board on the conveyor passes. The surrounding wall (9) of the heating chamber has vacuum layers (12) (13) for heat insulation, and a reinforcing rib (19) is fastened to the surrounding wall. A member for preventing collapse of the surrounding wall is inserted and secured in the vacuum layer in the surrounding wall. The member includes a stainless steel channel member (17) and a heat insulating plate (18) with a rectangular cross section. White cotton used as a member (20) for intercepting radiant heat is installed within the vacuum layer in the surrounding wall, and a radiant heat reflective layer (22) of aluminum foil, etc. is installed on the surface of the surrounding wall facing the heating chamber.