A laser device provided with the function of predicting occurrence of condensation and preventing occurrence of condensation in advance. The laser device is provided with a controlling part calculating a reference temperature for judging whether a cooling water feed device may feed cooling water based on a temperature measured by a thermometer and a humidity measured by a hygrometer, and a comparing part comparing a reference temperature and a cooling water temperature. The cooling water feed device is configured to stop the feed of cooling water after a command for starting up the laser oscillator has been output and the cooling water temperature is lower than the reference temperature and to start or continue the feed of cooling water when the cooling water temperature is the reference temperature or more.