The invention provides a laminated resin molding, its manufacturing method, and its manufacturing apparatus. Provided is a molding apparatus (50) or an apparatus for manufacturing a laminated resin molding, which is composed of a female mold (52), a first horizontal mold (54), a second horizontal mold (56) and a male mold (58), and these components form a cavity (60). This cavity (60) includes a horizontal portion (64) extending in a horizontal direction, and a first vertical portion (66) and a second vertical portion (68), which rise substantially vertically from the horizontal portion (64). The first vertical portion (66) has a vertical size set larger than that of the second vertical portion (68). In the male mold (58), an injector (22) is disposed at a portion corresponding to the substantially central portion of the horizontal portion (64), and an air supply pipe (30) is disposed at a portion corresponding to the second vertical portion (68). When a raw material (28) is injected from the injector (22) so as to execute the laminated resin molding manufacturing method, a gas such as compressed air is introduced through the air supply pipe (30) into the second vertical portion (68), so that the raw material (28) is pushed by that gas to the side of the first vertical portion (66).