PURPOSE: To always fetch an appropriate electric image signal irrespective of both thickness of an object to be photographed, in a short time, and also, by simple device constitution.

CONSTITUTION: In a radiograph reader for reading a radiograph formed in accordance with the transmission quantity of radiant ray for transmitting through an object to be photographed, the gain of a suitable circuit in a reader main body 3 is set in accordance with body thickness by a gain control circuit 12, according to both thickness measuring signal from a body thickness measuring instrument for measuring the body thickness of the object. Also, a recording scale factor of A/D conversion may be set instead of the gain. Moreover, the image processing condition of a gradation processing, etc., is adjusted in accordance with the body thickness.