PURPOSE: To satisfactorily perform the division of a substrate by so placing a thin plate that the face formed with the cut grooves of the substrate is opposed to a thin plate having specific Young's modulus, and pressing the cut groove top not formed with the cut groove of the substrate by a pressing member.

CONSTITUTION: Many chips 2 are formed in an arranging manner, and an adhesive tape 6 adheres to the other main face having no cut groove 3 of a wafer 1 formed with lateral and longitudinal cut grooves 3 on one main face. Then, the wafer 1 is so disposed that the main face with the grooves 3 is disposed at a protective sheet 5 side through the sheet 5 on a thin plate 12 having 6×1011 dyn/cm2 or more of Young's modulus and the direction of the grooves 3 coincide with the extending direction of a roller 15. When the roller 15 is rotatably moved on the upper face of the tape 6, the wafer 1 is bent at a thin part 8 as a fulcrum, and collapsed at this part. The wafer 1 is rotated at 90°, and the roller 15 is moved. Then, the wafer 1 can be divided into many chips 2.