PURPOSE: To implement shading correction with simple constitution by obtaining a correction data based on a correction reference data resulting from averaging processing so as to reduce the correction data quantity.

CONSTITUTION: A stimulated light 34 from a laser light source 33 is reflected and polarized by a high speed rotary polygon mirror 36 and collected and a stimulated phospoher sheet 1 is main-scanned in the direction of the arrow X while the optical path is changed. A stimulated luminous light 39 in response to radiation ray picture information stored and recorded radiateds from the sheet 1 and is made incident from an incident end face 40a, received and detected by a photo multiplier 41. An analog output signal S from the multiplier 41 is compressed and corrected and A/D-converted to obtain a digital read picture data Sb. The data Sb is subject to averaging processing by one rotation of the polygon mirror 36 at a processing means 45, subject to gradation and frequency processing and the result is inputted to a picture reproduction means 47. Thus, the radiation ray picture stored and recorded on the sheet 1 is reproduced as a visual image by using the data Sb.