1. A charged particle beam device, comprising: a charged particle source; a deflector which scans a sample with a primary charged particle beam emitted from the charged particle source; an objective lens which converges the primary charged particle beam emitted from the charged particle source; a detector which detects signal electrons which are generated from the sample by irradiation with the primary charged particle beam; a memory which stores a detection signal from the detector; and a control apparatus which processes the detection signal, wherein: the detector includes detection elements arranged in a planar manner; the detector detects, for each irradiation position on the sample, distribution information of the signal electrons emitted from the irradiation position; the memory stores the irradiation position and the distribution information of the signal electrons emitted from the irradiation position in association with each other; and the control apparatus calculates a pixel value for each irradiation position on a basis of the stored distribution information of the signal electrons for each irradiation position, and forms an image by associating the calculated pixel value with each irradiation position.