A composite molded body includes a main portion formed of resin, a ventilation channel configured within the main portion, a gas permeable membrane, and two inserted members embedded in the main portion. The ventilation channel has a first ventilation path P1 extending in a direction intersecting the gas permeable membrane and has an opening end leading to the external air, and a second ventilation path extending in a direction different from the direction in which the first ventilation path extends and having an opening end leading to the internal space of the casing. The inserted member forms a portion of the second ventilation path and has a membrane supporting portion formed with a through hole. The through hole constitutes a portion of the first ventilation path, and communicates with the internal space of the casing via the second ventilation path.