Topology optimization is applied for the optimal design of various products to ensure weight reduction andproductivity improvement. Reducing the weight of the mold while maintaining its rigidity can ensure shorteningof the production cycle, stabilization of the mold temperature, and reduction of mold material costs. In thisstudy, a topology optimization technique was applied to the optimal design of the injection mold, and atopology-optimized model of the mold was obtained. First, the injection mold for the square specimens wasmodeled. Subsequently, a structural analysis was performed by implementing a load condition generated duringthe injection molding process. Topology optimization was performed based on the structural analysis results, andthe models of the initial and topology-optimized designs were manufactured at 1/4 magnification using a 3Dprinter. Consequently, compared with the existing model, the weight of the topology-optimized model decreasedby 9.8%, and the manufacturing time decreased by 7.61%.