To prevent an output decrease of laser light due to impurities formed in a Q switch. A laser machining device includes a Q-switch housing section configured by housing a Q switch and a first mirror and a wavelength converting section including a housing in which a transmission window section capable of transmitting a fundamental wave is formed, the wavelength converting section being configured by airtightly housing, with an internal space surrounded by the housing, at least a first wavelength conversion element, a second wavelength conversion element, and a second mirror. A resonator forming a resonant optical path passing through the transmission window section is configured by the first mirror in the Q-switch housing section and the second mirror in the wavelength converting section.