A laser processing apparatus which can suppress the positional fluctuation in light-converging point of laser light during laser processing is provided. On an optical path of laser light L1 connecting a beam expander 34 and a first light-transmitting hole 32 of a lens holder 29 to each other in a laser processing apparatus 20, a stop member 38 including a second light-transmitting hole 39 having the same diameter as that of the first light-transmitting hole 32 is disposed. Hence, the amount of laser light L1 cut by the surrounding part of the first light-transmitting hole 32 can substantially be eliminated, whereby the lens holder 29 can be prevented from being heated upon irradiation with the laser light L1. Also, even when the stop member 38 is heated by the laser light L1 cut by the surrounding part of the second light-transmitting hole 39, heat is prevented from being transmitted from the stop member 38 to the lens holder 29, since the stop member 38 is separated from the lens holder 29. Therefore, the positional fluctuation in light-converging point P1 of the laser light L1 during laser processing can be suppressed to a low level.