PURPOSE: To provide a press molding method wherein a polyolefinic resin having a good coating adhesiveness and a reduced molding strain is produced.

CONSTITUTION: In the press molding of a polyolefinic resin containing a functional polyolefinic resin 5-100wt.% having at least one functional group selected from a hydroxyl group, an amino group, a carboxylic acid group, a carboxylic anhydride group and an epoxy group bonded thereto, the molten polyolefinic resin is supplied to the cavity between press molds using an injection molding machine and at least one of the press molds is moved to subject the polylefinic resin to press molding. By this method, a polyolefinic resin molded product excellent in painting close adhesiveness can be molded in a high cycle without applying painting pretreatment such as trichloroethane washing or primer treatment.