In a device to deliver a powdery medicine into a nasal cavity, one-way valve 33 is built in an air flow passage 31 of a capsule housing/holding part 30, the one-way valve 33 is controlled for the opening pressure by a spring 34 and opens by a pressure of air from the pump 50, the one-way valve end 71 does not interfere the setting/detaching operation of the capsule setting/detaching part 40 and the capsule K when the one-way valve 33 is opened and intrudes as far as the inside of the capsule to disperse the medicine in the capsule K when the one-way valve 33 is opened by pressing of the pump 50 upon dosing thereby capable of reliably dosing at a adequate dose also including the medicine falling as far as the one-way valve 33 to the nasal cavity of the user.