A blow molding apparatus includes: an injection molding section for injection molding a plurality of preforms at a time; a cooling section for cooling the preforms; a heating section for heating the preforms while continuously transporting them along a transport line; and a blow molding section for blow molding the preforms to form hollow containers. The blow molding section includes a primary blow molding section which is equipped with a heat-treating blow mold and blow molds the preforms moved from the transport line into the heat-treating blow mold to form intermediate molded products, and a secondary blow molding section which is equipped with a final blow mold and blow molds the intermediate molded products moved from the heat-treating blow mold into the final blow mold to form the hollow containers.