A laser device includes an optical fiber laser unit including an amplification optical fiber, a plurality of pumping light sources outputting pumping lights for optically pumping the amplification optical fiber, and a controller controlling the pumping light sources. When an instruction value for supplying a predetermined driving electric current to each of the pumping light sources is input to the controller, the controller conducts a control of supplying a compensated electric current value as a driving electric current obtained by multiplying an initial electric current value corresponding to the instruction value by a compensation coefficient and supplying the compensated electric current value to each of the pumping light sources. The compensation coefficient is set to restrain a decrease in a power with time of a laser light output from the optical fiber laser unit.