A user inhales medicine ejected from the medicine ejecting section of an inhaler into the air flow duct of an air flow duct forming member through a hole. As the air flow duct forming member is taken off from the inhaler body, the medicine ejecting section is covered by a cap for protection. As the air flow duct forming member is fitted to the inhaler body, the cap is opened and a sensor recognizes the open state of the cap so that the air flow duct forming member is prohibited from being fitted to and taken off from the inhaler body by a claw that is secured to the air flow duct forming member. In this way, the medicine ejecting section is prevented from being damaged when the air flow duct is fitted to and taken away from the inhaler.