PURPOSE: To improve the accuracy of the outer dimensions of an image sensor chip by a method wherein, after trenches are formed in the active plane of a board on which a plurality of image sensors are provided, an ultraviolet-curing type adhesive member is applied and, further, trenches are formed in the plane of the board opposite to the active board.

CONSTITUTION: The rear 4 of a wafer is fixed to a cutting apparatus 7. Trenches are formed in the active plane 3 of the wafer along the end surfaces 5 of the longitudinal direction of respective image sensor chips 1. In order to protect the active plane 3 of the wafer when trenches are formed in the rear 4 of the wafer, an ultraviolet-curing type adhesive member 9 is applied to the active plane 3 in which the trenches are formed. The active plane 3 side of the wafer is fixed to the cutting apparatus 7 and trenches are formed in the rear 4 along the end surfaces 5 of the longitudinal direction of the respective image sensor chips 1. A cracking process is performed while the ultraviolet- curing type adhesive member 9 is bonded to the wafer 2. An ultraviolet radiation 11 is applied to reduce the bonding strength of the ultraviolet-curing type adhesive member 9 to separate the respective image sensor chips 1.