To accurately execute shading correction in a short time.

In executing shading correction, information related to points Dn1, Dn2, Dn3 on a correction curve required for generating only a correction curve corresponding to a present focal length of an optical system is stored in a main storage part from a data table previously stored in an auxiliary storage part. A correction curve Sn' is generated based on the information. Thereby, the volume of information related to the correction curve which is handled at a time is reduced in executing shading correction, and an occupation area of the main storage part as a working area of a control part is resultantly reduced, Accordingly, the shading correction can be rapidly executed.