A laser beam source device includes a light source that emits light of a first wavelength, a wavelength converting element that converts a wavelength of the light of the first wavelength entered into a second wavelength, a multi-layer film mirror having a characteristic of reflecting light of the first wavelength and transmitting light of the second wavelength, a band-pass filter having a band-pass characteristic near the first wavelength is formed, a reflection mirror that branches the light transmitted through the multi-layer film mirror to the first optical path and a second optical path, a laser-power measuring unit that measures power of the light branched to the second optical path, and a control unit that performs angle adjustment for displacing a tilt angle of the band-pass filter.