PURPOSE: To obtain a high quality image which is free from noise and excellent in resolving power, sharpness and gradation, by preventing the titled reader from projecting an excitation light beam to the vicinity of the outside of a read area extending from a scan start point to an end point for reading and exposing an image part on a converting panel.

CONSTITUTION: By detecting a fact that a laser beam L has passed through the other end of the photodetecting window width of a photodetector 51, or inputting a counting signal of a clock count, the light emission of the laser beam L is stopped and an incident light to a conversion panel 3 is turned off. Subsequently, a prescribed second time by the clock count is elapsed, the laser beam L is turned on again, and this time point is immediately before one end R of an image information read area. When the laser beam L is turned on again, read of image information is started. The other end E of the image information read area is in a position where the laser beam L passing through an opening end of a slit 49A of a beam stopper 49 is turned off, and almost simultaneously, an image signal on a main scanning line is ended. In such a way, it is prevented that an unnecessary light enters onto the main scanning line of the converting panel 3.