PURPOSE: To obtain a resin made hollow container having a bulge by a signel process smoothly and favorably, by using a mold of which both of an inner mold and an outer mold are divided into plural pieces and the butting parts of the split outer molds each other and the inner molds and the outer molds have a shear edge structure.

CONSTITUTION: A mold which is constituted from the split molds of both of an inner mold and an outer mold divided respectively two or more pieces and has a shear edge structure at the butting parts of the split outer molds each other and the inner molds and the outer molds is prepared. A clearance of the shear edge is made ca. 0.02W0.05mm, an intermeshing depth is less than ca. 10mm and a shear edge angle is ca. 3W5°. Then, press molding is performed by using a plastics material for press molding composed of a thermoplastic or thermosetting resin as a base resin. By this, the resin material does not be forced out to the butting parts of the molds each other and a hollow synthetic resin molded product having a bulge of a water container,a fuel container etc. is obtained smoothly.