An injection molding apparatus includes a first upstream mold having a first gate opening into which a first molding material flows, a second upstream mold having a second gate opening into which a second molding material flows, a first injection unit injecting the first material through the first gate opening, a second injection unit injecting the second material through the second gate opening, and a downstream mold clampable with each of the first and second upstream molds. The second material is injected by the second injection unit after the first material is injected by the first injection unit. The second gate opening is separated further from the downstream mold than the first gate opening, and a volume of a second cavity partitioned by the second upstream mold and the downstream mold is larger than that of a first cavity partitioned by the first upstream mold and the downstream mold.

An injection molding apparatus includes a first upstream mold having a first gate opening into which a first molding material flows, a second upstream mold having a second gate opening into which a second molding material flows, a first injection unit injecting the first material through the first gate opening, a second injection unit injecting the second material through the second gate opening, and a downstream mold clampable with each of the first and second upstream molds. The second material is injected by the second injection unit after the first material is injected by the first injection unit. The second gate opening is separated further from the downstream mold than the first gate opening, and a volume of a second cavity partitioned by the second upstream mold and the downstream mold is larger than that of a first cavity partitioned by the first upstream mold and the downstream mold.