A device for exterminating pests having a cylinder filled with carbon dioxide in which (a) pesticide(s) is(are) dissolved, piping coupled to the cylinder, and a plurality of capillary nozzles affixed to the piping, and a method of exterminating pests employed this device. The capillary nozzles are designed such that, considering adjacent capillary nozzles, the ratio of the nozzle exit area of the capillary nozzle close to the cylinder to the nozzle exit area of the capillary nozzle remote from the cylinder is set between 1:1.3 and 1:1.8. As a result, numerous independent enclosed spaces can be sprayed with little labor and in a short time by means of a small number of devices.