Provided is a charged particle beam apparatus capable of estimating an internal device structure of a sample. The charged particle beam apparatus includes an electron beam optical system, a detector, and a calculator. The electron beam optical system irradiates a plurality of irradiation points on a sample, which are different in position or time, with an electron beam. The detector detects electrons emitted from the sample in response to irradiation of the electron beam by the electron beam optical system. The calculator calculates a dependence relationship between the irradiation points based on the electrons detected by the detector at the plurality of irradiation points.