A method of specifying affected parts characterized by comprising the steps of detecting radiation emitted from a human body in a pinpointed manner by a radiation detector (1), inputting a detected radiation dose or intensity to a computer (3), and displaying radiation doses or intensities at respective portions of the body on a body distribution diagram on a monitor screen (4). The above radiation doses or intensities are measured while the radiation detector (1) is being gradually distanced from the body, and maximum distances at which the radiation detector can detect radiation rays are set as measurements, thereby obtaining data simply.