A laser processing apparatus including a laser oscillator, a laser processing machine, and a control part controlling the laser oscillator and the laser processing machine. The control part includes a preparatory operation part controlling the laser processing machine so as to start a preparatory operation for the laser processing if a preparatory operation command is output and, a mode switching part switching an operating mode of the laser oscillator between a standard standby mode before carrying out the laser processing and an energy saving mode with less consumed power than the standard standby mode, and the mode switching part controls the discharge tube voltage so as to switch the operating mode to the energy saving mode before the preparatory operation command is output and to start a switching operation of the operating mode from the energy saving mode to the standard standby mode when the preparatory operation command is output.