A charged particle beam apparatus automatically prepares a sample piece from a sample. The apparatus includes a charged particle beam irradiation optical system that emits a charged particle beam. A sample stage with a sample placed thereon is movable relative to the charged particle beam irradiation optical system. A sample piece transferring device holds and transports a sample piece separated and extracted from the sample, and a holder fixing base holds a sample piece holder to which the sample piece is to be transferred. An electrical conduction sensor detects electrical conduction between the sample piece transferring device and an object, and a computer sets a time management mode when electrical conduction between the sample piece transferring device and the sample piece is not detected when the sample piece transferring device and the sample piece are connected to each other.