Dicing method and laser processing apparatus

A laser processing apparatus comprising:

• a chuck table configured to hold a substrate;
• a processing laser light source configured to emit laser light;
• a processing lens configured to cause the laser light to irradiate the substrate;
• a first distance sensor configured to measure a first distance between a first position of the substrate and the first distance sensor;
• a second distance sensor configured to measure a second distance between a second position of the substrate and the second distance sensor, the second position different from the first position, the processing lens being located farther from the second distance sensor than from the first distance sensor;
• a calculation circuit configured to calculate a distance between the substrate and the processing lens based on the first distance and the second distance;
• and
• a substrate moving unit configured to move the substrate.