PURPOSE: To obtain a laser driving device which can be readily used by storing an operation signal when a semiconductor laser is initially operated, monitoring an operation signal at real using time, and comparing both signals to generate an abnormal alarm, thereby detecting the deterioration before the life of a laser is wasted.

CONSTITUTION: A laser driving program and/or information is stored in a ROM 81, digital information corresponding to a driving circuit set to the ROM 81 is stored in a RAM 82, and digital information corresponding to a driving current at load time is stored as an initial value in a RAM 83. A driving circuit 2 receives a write information signal 21 and a laser output regulation signal fed through a D/A converter 3 and drives a laser 1. The laser output is monitored by a photodiode 5, compared by a CPU 4 through an LPF 6 and an A/D converter 7, and an abnormal alarm 9 is generated. According to this construction, an alarm is generated before the life of the laser is wasted, thereby readily performing a maintenance.