The light-emitting device includes: a setting unit switching a potential difference between anode and cathode electrodes alternately between first and second potential differences so that light-emitting thyristors are caused to have one of the first and second potential differences in common; a specifying unit sequentially specifying, as a target for controlling, one light-emitting thyristor; a supply unit alternately supplying transition voltage for causing specified light-emitting thyristor to transition from the off state to the on state and maintaining voltage for keeping the thyristor being in the off state to a gate electrode of the thyristor, in a light-emission control period during which the specifying unit specifies the target and the setting unit sets the second potential difference; and an adjusting unit that adjusts a light-emitting period of the one light-emitting thyristor by supplying the maintaining voltage and stopping supplying the voltage at a variable timing, in the light-emission control period.