An optical writing device having; a plurality of light-emitting points; a plurality of drive circuits for supplying drive currents to the plurality of light-emitting points respectively; a photodetector for outputting signals indicating quantities of light entering thereto from the respective light-emitting points; a gain switch circuit for outputting photodetection signals obtained by amplifying the signals output from the photodetector in regard to the respective light-emitting points with gains preset for the respective light-emitting points; and a control circuit for controlling the drive circuits such that the photodetection signals output from the gain switch circuit in regard to the respective light-emitting points coincide with a value substantially equal to a predetermined reference value. The gains for the respective light-emitting points are preset based on the distances between the photodetector and the respective light-emitting points.