Laser processing method of wafer

A laser processing method of a wafer in which a wafer having a device in each of regions marked out by a plurality of planned dividing lines set on a surface in a lattice manner is processed by using a laser processing apparatus including a laser beam irradiation unit having a laser beam oscillator that oscillates a pulse laser beam with such a wavelength as to be absorbed by the wafer, a laser beam splitting unit, and a collecting lens and having a function of irradiating, through the collecting lens, the wafer held by a chuck table with a plurality of laser beams formed by being oscillated by the laser beam oscillator and being split by the laser beam splitting unit, the laser processing method comprising:

• a holding step of holding the wafer by the chuck table;
• and
• a processed groove forming step of irradiating the wafer with the plurality of laser beams along the planned dividing line and forming a processed groove along the planned dividing line in the wafer,
• wherein, in the processed groove forming step, the plurality of laser beams split by the laser beam splitting unit are arranged in a line manner along a direction that is non-parallel to an extension direction of the planned dividing line irradiated with the plurality of laser beams.