To provide a laser dicing method capable of performing stable cutting and preventing deterioration in the quality of a divided wafer piece.

A dicing process includes a groove section formation step for forming a groove section 22 in which stress can concentrate by tensile force on a back 21b of a scheduled cutting line DL to depth reaching a modified layer K. As a result, a range where no modified layers K are formed is not present on a surface layer Ws on the back 21b of the scheduled cutting line DL in which the groove section 22 is formed, while stress concentrated at the groove section 22 is directly applied to the modified layer K leading to the groove section 22 when tensile force is applied in cutting, thus promoting the growth of cracks starting from the modified layer K and hence greatly reducing the possibility of the development of the growth of cracks in a non-scheduled direction as compared with a case where the range in which no modified layers K are formed on the surface layer Ws in the schedule cutting line DL is present, and preventing the deterioration of the quality of a divided chip CP by realizing stable cutting.