PURPOSE: To smoke an expellent by a gas generated by ignition means provided in a chamber in the lowest stage in a device consisting of the chamber in the lowest stage filled by combustion agent and upper chamber in one stage or plural stages filled by insect pest expellent.

CONSTITUTION: In an expellent smoking device 1 made of sheet, etc., obtained by laminating a thermoplastic resin to Al, a combustion agent 4 and ignition member 5 are housed in the lower chamber 1a and granular expellent 6 obtained by blending the expellent with an auxiliary combustion agent and granulating the blend is filled in the upper chamber 1b having installed opening part 7. A gas generated by igniting to a combustion agent (e.g. containing a perchloric acid salt, chloric acid salt, nitric acid salt, nitro compound, peroxide, etc., and saccharides containing polysaccharides as a reducing agent) is introduced into the upper chamber, where the expellent is vaporized and accompanied by the gas and released to outside by opening 7. The aid combustion agent includes guanidine nitrates, nitrocelluloses having low nitrogen content, etc. The expellent is free from change with the lapse and the device also has simple structure.