Dosimeters with an environmental safety are provided, by which a dose of radiation can be measured in real time when taking or fluoroscopically viewing an image by using the radiation while suppressing influence on the image taken or fluoroscopically viewed. The present dosimeter comprises a radiation detection part 100 including a phosphor 120 made of Y2O2S as a matrix with at least Eu as an activating agent, an optical fiber 200 of transmitting light emitted from the phosphor 120 of the radiation detection part 100 by receiving a radiation, and a light detection part 310 of detecting the light transmitted through the optical fiber 200.
