A sound output portion 7, a power supply switch 4, and a power supply portion 3, which are provided at a detachable portion A of a manipulation grip 1 are configured to be detachable from a main body portion B of the manipulation grip 1. Accordingly, upon sterilization using a sterilizing gas such as an EOG, the sound output portion 7, the power supply switch 4, and the power supply portion 3 can be removed on a detachable portion A basis. This in turn allows for using a sterilizing gas such as EOG to sterilize the radiation detector except the sound output portion 7, the power supply switch 4, and the power supply portion 3, thereby preventing damage caused by a negative pressure in the sound output portion 7.