A radiation detector has a main body (1), and a radiation detection probe (2) detachably attached to the distal end of the main body (1). The probe (2) includes a detection unit (3) accommodating a radiation detection element (7), a cap-shaped shield member (6) mounted to the detection unit (3) so as to cover the distal end of the detection unit (3), and a probe cover (4) accommodating the detection unit (3) and the shield member (6). A connector (10) onto which the probe (2) is adapted to be screwed is provided on the distal end of the main body (1). A collimator (6A) for collimating incident radiation is provided on the distal end of the shield member (6).
