To provide a method for manufacturing an injection-molded article that can control an amount of flash generated during molding, and obtain a molded article of a high degree of crystallinity.In injection molding of a polyarylene sulfide resin composition, injection molding is performed using a mold having a heat-insulating layer formed on an inner surface of a mold, and at a mold temperature of 100° C. or less.It is preferable for the thermal layer to have a thermal conductivity ratio of 5 W/(m·K) or less.Furthermore, a composition including a polyimide resin can be exemplified as a preferable heat-insulating layer.The heat-insulating layer is preferably the one including a polyimide resin.