The present invention addresses the problem of providing a technique with which it is possible to easily carry out molding and to suppress deformation of an insert member when producing a resin molded article using an insert member that has low pressure resistance. This method for producing a resin molded article includes a step for disposing an insert member in the cavity of a mold, a step for injecting molten resin into the cavity, a step for terminating injection after the molten resin reaches an overflow portion in the cavity and before the molten resin fills the overflow portion, and a step for separating the resin of the overflow portion.本發明之課題係提供在使用耐壓力低之插入構件並製造樹脂成形物時，可容易進行成形，且可抑制插入構件之變形的技術。本發明之樹脂成形物的製造方法係包含以下步驟：於模具之模槽配置插入構件；於該模槽內注入熔融樹脂；該熔融樹脂到達該模槽內之溢出部後，在該熔融樹脂注滿該溢出部前結束該注入；及將該溢出部之樹脂予以分離。
