A laser processing apparatus includes: a laser beam radiation part that radiates a laser beam to a target position on a substrate; a liquid supply source; a liquid supply nozzle that is connected to the liquid supply source through a liquid supply channel; a guide member for the ejected liquid; and a movement mechanism that allows a substrate holding part, and the laser beam radiation part, the guide member and the liquid supply nozzle to relatively move in a horizontal direction in a state that a center of a radiation spot of the laser beam is in a projection region on the substrate when the liquid ejection port of the liquid supply nozzle is extended in an ejection direction.