PURPOSE: To make precision cutting free of bending at all times by sensing alway accurately the inclination of a saw element during sawing, and thereupon correcting eventual inclinations.

CONSTITUTION: An endless saw element 1 is set over pulleys 2, 3 and moved at a specified speed by a motor 4. To this saw element 1, a work to be processed 5 fixed to a table 6 is fed by another motor 7, and cutting the work is conducted. During sawing, the inclination of the saw element 1 is sensed contactlessly by an optical head 9 positioned substantially as mating the tips of the teeth, and the generated sensing signals are fed to a computational processing circuit 10 to undergo a computational processing, and the resultant signals obtained are passed to a PWM control circuit 11 to serve controlling the operation of the drive motor 7. With this control of the feeding speed made by the motor 7, eventual inclination of the saw element 1 is corrected, and vertical cutting free of bending is achieve.