PURPOSE: To improve the workability by inputting the thickness l of a material to be cut and a cutting rate (μ) based on the material and calculating the optimal cutting speed V then performing the cutting control of a saw cutter.

CONSTITUTION: A cutting speed V is outputted from an operation control circuit 20 through an output port 24 while the thickness (l) and the cutting rate (μ) of a material G to be cut are inputted through a keyboard 25 to said port 24. The output from the port 24 is inputted to an interface circuit 27 the output of which is inputted to a drive control circuit 30 for a motor 5. The controlled motor 5 will rotate a lead screw 4 to move a vertical saw frame 3, thus cutting the material G with the optimal cutting speed V.