The invention solves charge nonuniformity of a specimen surface resulting from emission variation of a carbon nanotube electron source and individual difference of emission characteristics. During charge control processing, charge of the specimen surface is measured in real time. As means for solving charge nonuniformity resulting from nonuniformity of electron illumination density, electrons illuminating the specimen and the specimen are moved relatively to average electron illumination density. Moreover, an absorption current flowing into the specimen and the numbers of secondary electrons emitted from the specimen and of backscattered electrons are measured as means for monitoring charge of the specimen surface in real time.