According to a charged corpuscular particle beam irradiating method of this invention, a focusing element (19) which focuses the trajectories of charged corpuscular particles (12) emitted from a specimen (10) is arranged at a position which prevents focusing action by the focusing element (19) from affecting a charged corpuscular particle beam (4) traveling toward the specimen or can curb effects of the focusing action on the charged corpuscular particle beam (4). With this configuration, the focusing action selectively affects the charged corpuscular particles (12) emitted from the specimen (10), and effects of the focusing action on the charged corpuscular particle beam (4) traveling toward the specimen (10) are curbed. Thus, charged corpuscular particles emitted from the specimen (10) and traveling in a direction other than a direction toward a detector and the like can be focused and guided into the detector and the like, and a charged corpuscular particle beam irradiating method capable of efficiently detecting a charged corpuscular particle traveling in a direction other than the direction toward the detector and the like can be provided.