An object is to provide an aluminum die cast product, e.g., a pressure vessel that requires high airtightness, in which pressure leak or gas leak ratio can be reduced and the product yield can be increased and also to provide a method for manufacturing the product. An aluminum die cast product in which a cast hole (2A) is formed by a core pin (5) in a thick portion (4) that is made thicker than other portions, wherein a chill layer (2B) with a secondary dendrite arm spacing of at least 5.5 µm or less is provided at the surface of the cast hole (2A).