To provide a light emitting element driving device that performs supply voltage control respectively optimal for a case when cathode voltages of all light emitting elements are low and a case when the cathode voltage of a light emitting element only at one place is low.

The light emitting element driving device includes: a voltage control circuit 1; a plurality of light emitting element arrays constituted of a plurality of light emitting elements 2 to 7 which emit light in accordance with levels of supplied currents; and constant-current drive control parts 8 to 10 connected to the light emitting element arrays in series respectively. The respective light emitting element arrays are further connected to a plurality of gm amplifiers 11 to 13, and comparisons with a reference voltage 14 are made. When the gm amplifiers 11 to 13 output currents based on the voltage errors, in accordance with the composite current of the output currents of the gm amplifiers 11 to 13, the voltage control circuit 1 adjusts an output voltage VOUT output to the light emitting elements 2 to 7.