To read stimulated emission light with a reading part from a cumulative phosphor sheet on which radiograph information of an object is cumulatively recorded and to detect the quantity of light of an erase part that emits remaining radiation energy by radiating erasing light from a light source after finishing the reading.

A CCD line sensor 40 for reading stimulated emission light detects the quantity of erasing light Q reflected from the cumulative phosphor sheet IP. That is, the reading part 14 is also employed as a detecting part for detecting the light of quantity of a fluorescent lamp 42 of the erasing part 16.