PURPOSE: To accurately correct the decrease of an emitting light intensity due to the aging change of a light emitting element by modifying the emitting light intensity correction value of the element having high use frequency in response to the use frequency of the element when the frequency of the element of a light source such as an electrophotographic printer, etc., becomes high.

CONSTITUTION: An electrophotographic printer has an LED array 3 as a light source in which a plurality of LEDs are arranged on one row along a light emitting drum, and includes a memory 1 for correction data to store correction data having emitting light intensity correction value of the array 3. Image data formed by developing print data from the exterior in a dot pattern by an image forming apparatus 2 and energization data of the LED by a light quantity correcting unit 5 based on the correction data of the memory 1 are formed. The conducting data of the LED is formed based on the correction data of the memory 1 by the correcting unit 5. In this case, the emitting light intensity correction value of the LED having high use frequency of the correction data of the memory 1 is so individually modified as to raise the emitting light intensity of the LED.