A laser driver circuit comprising a current supply circuit for supplying a laser diode with a current is provided. The current supply circuit comprises a voltage-to-current converter circuit, a current output line for outputting the current generated by the voltage-to-current converter circuit, a current supply line connected to the laser diode, a ground line connected to the ground, and a current path switch for selectively connecting either the current supply line or the ground line to the current output line. The laser driver circuit further comprises a current output prevention circuit for preventing the voltage-to-current converter circuit from generating the current by disconnecting the voltage input line using a voltage input switch so that the voltage is not input to the voltage-to-current converter circuit, when the current output line and the ground line are connected by the current path switch.