PURPOSE: To mold a molded product without sink and without lowering strength, blister and the like on a wall section caused by the generation of hollow sections by providing a gas path having the width larger than the wall thickness of a section from which the gas is forced in and the height larger than the wall thickness by specified times on the rear face of a molded product.

CONSTITUTION: A mold consists of a fixed mold A and a movable mold B, and the movable mold B is provided with a cavity section 1 forming a wall section of a molded product to be molded and a gath path 3. The width (w) of the gas path 3 is larger than the wall thickness (t) of a section from which the gas is forced in and the height (b) is more than the wall thickness by 3t or more. When the width (w) of the gas path 3 is less than (t) or the height (h) of the gas path 3 is less than 3t, the gas is flowed on the wall section of the molded product to generate hollow sections 7 on the wall section. A molded product without sink and without gas flowing on the wall section of the molded product can be manufactured by using the mold with the gas flow path 3 forming a gas forcing inlet all through the rear face of an uneven wall section of molded product, a thick wall or the like.