In a laser apparatus, a rotatable reflection mirror rotatable on or parallel to a resonance optical axis of a laser medium is disposed changeably between a first and second positions by driving of a rotating unit. A first resonance optical system includes a first and second resonant mirrors placed so that the laser medium and the rotatable reflection mirror disposed in the first position are interposed therebetween to resonate light of a first peak wavelength among the peak wavelengths emitted from the laser medium, the first peak wavelength light being to be reflected by the rotatable reflection mirror in the first position between the laser medium and the second resonant mirror, and a first wavelength converting element located between the rotatable reflection mirror disposed in the first position and the second resonant mirror to oscillate second harmonic light of the first peak wavelength light as a first laser beam.