PURPOSE: To eliminate the necessity to use an expensive molding machine or a mold and reduce the cost by vulcanizing under pressure a flat substrate made of synthetic rubber in a bellows shape to make it a protective material proper and sewing it so as to correspond to glenoid stooping portions of a body.

CONSTITUTION: A flat substrate 1 made of synthetic rubber such as chloroprene sponge rubber is fed into a press hot plate 5 consisting of an upper mold 3 and a lower mold 4 with the press surface formed in a bellows shape 2, it is heated under pressure for a predetermined time and vulcanized, and a protective material proper A with a necessary size is formed by continuously performing this press work. This protective material proper A is positioned so as to correspond to glenoid stooping portions, e.g., shoulder, elbow, knee, etc., and a wet suit for underwater use, etc. is produced by sewing it. Thereby, there is no necessity to use an expensive molding machine or a mold, and also there is no limitation on the size of the molded object, thus freedom in machining can be obtained.