A radiation detector has a head and a main body. The head has a probe and a first joint. The probe has a radiation detector built in it. The probe is movable because of the first joint. A second joint that is a separate piece from the first joint is provided on the main body or the head, or between the main body and the head. This enables the radiation detector to move independently of the probe that is movable about the first joint. Operation freedom of the radiation detector is increased by the combination of movement about the first joint and that about the second joint. Therefore, the radiation detector has excellent operability.
