An optical device wafer dividing method includes a rear surface grinding step for grinding a rear surface of the optical device wafer; a dicing tape sticking step for sticking the front surface of the optical device wafer bonded with the reinforcing substrate to the front surface of a dicing tape; a laser processing step for emitting a laser beam along the streets formed on the optical device wafer from the rear surface of the reinforcing substrate to perform laser processing on the reinforcing substrate along the streets to form fracture starting points; and a wafer dividing step for applying an external force along the fracture starting points of the reinforcing substrate to fracture the reinforcing substrate along the fracture starting points to fracture the optical device wafer along the streets.