Laser machining apparatus

A laser machining apparatus in which laser output can be easily corrected in view of secular change of components of the laser machining apparatus and influence of temperature. Output values of a laser oscillator operated according to a reference laser output command value Psc are stored as reference output values P(theta) at different temperatures theta in a table TB 1 . When the laser oscillator is started up, a measured output value Pr of the laser oscillator supplied with the reference command value Psc is obtained, and a new correction coefficient k is obtained to replace an old one. From a reference output value P(theta) at a temperature at that time and the actual output measured value Pr, a correction value DeltaP is obtained and stored. Each time temperature theta is measured, a reference output value (Ptheta) at a measured temperature theta is obtained from the table TB 1 , an estimated output value Pa is obtained by subtracting the correction value DeltaP from the reference output value (Ptheta), and a new correction coefficient k is obtained to replace an old one. In other words, an output value at a different temperature is estimated on the basis of the correction value DeltaP obtained when the laser oscillator is started up, and a new correction coefficient k is obtained to replace an old one. When the temperature reaches a predetermined temperature, a new final correction coefficient k is obtained on the basis of the reference command value and a measured output value to replace an old one.