The multi-objective optimization method is used to define the standard deviation (SD) of temperature and average temperature of a product as objective functions to optimize the arrangement of cartridge heaters in an injection mold. We intend to shorten the mold heating time by maximizing the average temperature and minimizing the deformation of the product by reducing the SD of temperature. The design variables were defined as the depth and distance of the heater. After creating an approximate model using the DOE method, multi-objective optimization was performed using the generated approximate model to calculate the Pareto front. The developed method was applied to a square specimen for verification and then applied to a commercial model. Overall, the average temperature improved by at least 2% and SD of temperature improved by approximately 8% compared to the initial design.