To provide a two-layer injection-molded article which is advantageous to secure adhesive strength between a first resin layer and a second resin layer sufficiently even when applied to a large-sized product having a relatively thin wall.

While the first resin layer 2 of a first resin material is arranged in an injection molding mold, a second resin material which can adhere to the first resin material by a thermochemical reaction and is molded at a molding temperature higher than that of the first resin material is injected from a gate into the cavity of the mold in which the first resin layer 2 is arranged. In this way, the second resin layer 3 is formed, and the two-layer injection-molded article in which the first and second resin layers 2 and 3 are bonded together is produced. The second resin layer 3 has a wall-thickness gradient part 7 in which the wall thickness is increased gradually from a gate molding part 5 molded in a cavity part close to the gate toward a terminal molding part 6 molded in a cavity part close to the terminal.

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