PURPOSE: To reduce the amount of warps by controlling the flow rate of cooling/ washing liquids supplied to the tip of an inner blade on the basis of the passing flow rate of a flow adjustment valve and the displacement of the inner blade.

CONSTITUTION: A piping 9 is coupled to a cooling/washing liquid nozzle 7 arranged directing the inner edge of an inner blade 2, and a flowmeter 11 is connected with the piping 9, where a flow adjustment valve 12 is connected halfway in a water supply pipe on the inlet side. An output of the flowmeter 11 and a displacement recorder 14 is inputted to a blade displacement controller 13 to control the flow adjustment valve 12, and cooling/washing liquid amount data is outputted to the flow adjustment valve 12. Changing the flow rate of cooling/washing liquids during cutting of a silicon ingot in this way keeps a displacement of an inner blade.