Disclosed is an image reading method for reading an image on a document, including: reading cyclically the image in a main scanning direction with using an image pickup section, while relatively moving at least one of a light emitting section and the document irradiated by the light emitting section with a sub-scanning velocity in a sub-scanning direction perpendicular to the main scanning direction, against the image pickup section which comprises a plurality of light receiving elements in the main scanning direction; controlling, while the cyclic reading, a reading cycle in the main scanning direction to be inversely proportional to a magnification ratio; controlling, while the cyclic reading, light emitting intensity and light emitting period in the reading cycle to be constant irrespective of the magnification ratio; and controlling, while the cyclic reading, the sub-scanning velocity to be constant irrespective of the magnification ratio.