An injection molding apparatus for making a molding of fiber-reinforced synthetic resin which comprises a mold assembly having a molding cavity defined therein, into which a liquid molding material of synthetic resin containing reinforcing fibers is injected. The mold assembly has a gate defined therein, which gate has a thickness within the range of 0.2 to 0.4 times the thickness of a portion of the molding adjacent the gate, and also has a gate land of a length within the range of 10 to 20 times the thickness of the gate.