A device (1) for spraying powdery chemical agent includes a tubular guide member (21) to be installed in a container body (11), a gas generating agent (43) to be housed in a tubular part (26), a tubular rupturing member (31) for breaking a sealing part (41) to allow the gas generating agent (43) to fall in liquid within the container body (11), a piston (63) sliding airtightly against a lower side sliding inner peripheral wall (53) and defining an air space relative to an upper side diameter-enlarged inner peripheral wall (55), and a powdery chemical agent (3) to be stored on the piston (63).
