A driver circuit is provided which comprises a series-connected unit having a light-emitting element and a current limiting inductor directly connected to the light-emitting element, a regenerative diode which is connected in parallel to the series-connected unit and which regenerates energy stored in the current limiting inductor, a transistor which controls a current flowing through the light-emitting element and the current limiting inductor, and a controller which controls an operation of the transistor, wherein the controller controls the transistor according to a voltage value of a power supply applied to the light-emitting element.