PURPOSE: To automatically operate a diamond wire saw without fear of breakdown by providing a hydraulic operation unit having a cylinder and a piston disposed between a base and a movable base and coupled to either one to supply hydraulic oil to a side of pulling the saw of the cylinder.

CONSTITUTION: A driver for a diamond wire saw 28 to be used when stone is quarried from a mining place comprises a base 10 having wheels 12 and reversibly rotatable motor 15 for driving the wheels, and a movable base 17 longitudinally movably supported to the base 10 and having the motor 15 and a sheave 26 mounted with the saw 28 to be driven by the motor 15. A cylinder 21 and a piston 22 disposed between the base 10 and the movable base 17 and coupled to the base 10 and the movable base 17 are provided, and hydraulic oil is supplied from a hydraulic operation unit 20 to a side of pulling the saw 28 of the cylinder 21.