Provided is a charged particle beam device that outputs both an ion beam and an electron beam at a sample, has a common detector for both the ion beam and the electron beam in the charged particle beam device that processes and observes the sample, and is able to provide a detection unit to an appropriate position corresponding to the process details and observation technique of the sample. Provided are an electron beam optical column in which an electron beam for observing the observation surface of a sample is generated, an ion beam optical column in which an ion beam that processes the sample is generated, a detection device that detects a secondary signal generated from the sample or transmitted electrons, and a sample stage that is capable of mounting the detection device thereon; is rotatable in a horizontal plane that includes the optical axis of the electron beam and the optical axis of the ion beam about a cross point where both optical axes intersect; and is able to change the distance between the observation surface of the sample and the cross point.