An injection molding apparatus capable of minimizing cracks at the corners of a mold is provided. The injection molding apparatus includes first and second molds that mate with each other to define a molding cavity, a stationary member that supports the first mold, a movable member that supports the second mold and moves backwards and forwards together with the second mold, and a plurality of pressing members installed around the first mold so as to press a periphery of the first mold toward the molding cavity by a pressing force of the movable member when the first mold is mated with the second mold.