Abstract: An injection molding apparatus for producing a molded form having a thin thickness portion through injection molding, comprising: a metal mold; a cavity formed in the metal mold for molding the molded form; a degassing hole formed in a portion of the metal mold corresponding to the thin thickness portion of the molded form; a degassing pin inserted in the degassing hole and fixed thereat, the degassing pin being longitudinally divided into at least two divisional parts; whereby gas in the cavity is forcedly exhausted not only through a first air gap between an inner surface of the degassing hole and an outside surface of the degassing pin but also through a second air gap in an abutment portion between the divisional parts of the degassing pin.