The dosimeter device includes a carrier part (10), which includes a closed casing (11) formed of fixedly interconnected walls which enclose a measuring element (8) for detecting ionizing radiation, and fastening aids (12, 20) for the detachable fastening of the carrier part on a carrying device (1) which can be carried on a body part of a user, wherein the fastening aids are configured for defining the location of the fastening of the carrier part on the carrying device.