Abstract: A charged particle beam irradiation apparatus includes a specimen stage for holding a specimen; a specimen stage drive unit for moving the specimen stage; a detector for detecting the amount of displacement of the moved specimen stage; a charged particle beam optical unit for irradiating the specimen with a charged particle beam; an image display unit for displaying an image of the specimen, the image being formed by using charged particles or electromagnetic waves emitted from the specimen irradiated with the charged particle beam; a marker display unit for displaying a marker on each target position on an image of the specimen, on a viewscreen of the image display unit; a marker position input unit for designating reference positions on the image of the specimen; and a marker position calculation unit for calculating the position on which each marker is displayed on the image of the specimen on the viewscreen of the image display unit; wherein the position on the image of the specimen, on which each marker