A laser diode is initially secured on a substrate, and light emission is caused from the laser diode to radiate light, which is measured by a measuring instrument. The laser diode is positioned at a position where a maximum output is obtained. Subsequently, while continuing light emission from the laser diode, light output which passes through a solid state laser oscillator element with a reflecting surface is measured with the measuring instrument, and the solid state laser oscillator element with a reflecting surface is secured to the substrate at a position where a maximum output is obtained. Subsequently, light emission is caused from the laser diode to excite the solid state laser oscillator element to achieve the resonance of light between the reflecting surface and an output mirror, and laser beam which is output from the solid state laser oscillator element with a reflecting surface and which passes through the output mirror is measured with the measuring instrument, and the output mirror is secured to the substrate at a position where a maximum output is obtained.