PURPOSE: To greatly shorten time necessary for tool transfer preparation and tool exchange, by installing a tool exchange truck movable in the direction of the width of a workpiece and by providing support rollers on the top of the truck to support the workpiece.

CONSTITUTION: A shearer comprises a shearing frame 2 on a traverse base 1, an upper tool rest 4, a lower tool rest 6 and a tool exchange truck 9 on rails 8. To exchange a tool, an actuator 11 is swung to rotate tool exchange arms 17, 17' and support rollers 13 by about 180°. The tool exchange arm 17' whereon a new tool is previously set is oriented to the rest 6. The truck, 9 is moved again into the frame 2. New upper and lower cutters 6, 7 are then secured on the upper and the lower tool rests 4, 6. This results in greatly shortening time necessary for tool transfer preparation and tool exchange.