An imaging system includes an illumination portion, an imager, a reader, and an illumination controller configured to control an intensity of illumination light based on modulated illumination in a non-reading period. The modulated illumination has a first integrated light amount as a product of a variable intensity of a first pulse and an output period of the illumination light and a second integrated light amount as a product of a constant intensity of a second pulse and the output period. In the non-reading period, the illumination controller causes a predetermined light amount that is not larger than a maximum value of the first integrated light amount and is not smaller than a minimum value of the second integrated light amount to transit between the first integrated light amount and the second integrated light amount.
