A laser processing device includes a stage; a laser irradiation unit; an image capturing unit; a control portion configured to execute controlling the laser irradiation unit such that one or a plurality of modified regions are formed inside the semiconductor substrate when the wafer is irradiated with the laser light, determining whether or not a crack extending from the modified region is in a crack reaching state where the crack has reached a front surface side of the semiconductor substrate on the basis of a signal output from the image capturing unit, and deriving information related to adjustment of irradiation conditions of the laser irradiation unit on the basis of determination results.