PURPOSE: To prevent workmen's accident from occurring during cutting operation by a method wherein an air-actuated cylinder for actuating a hold-down member, an air-actuated cylinder for projecting a circular saw, a motor for travelling the circular saw and a motor for rotating the circular saw are controlled on the basis of the detection signal of a detecting switch, which is arranged on one side of the pressing face of the hold-down member.

CONSTITUTION: A contact type detecting switch 31 is arranged under the state being slightly dented below a pressure face (a) on one side of the pressing face (a) of a hold-down member 23 so as to be constituted to control an air-actuated cylinder 24 for actuating the hold-down member, an air-actuated cylinder 17 for projecting a circular saw, a motor 21 for travelling the circular saw and a motor 13 for rotating the circular saw on the basis of the detection signal of the detecting switch. In addition, the detecting switch 31 is constituted so as to have a contact constitution, which is a tape-like longitudinally continuous one. Accordingly, the detecting switch 31 surely actuates by being pressed with the elasticity, which is peculiar to the human body, when a finger tip is pinched by the hold-down member 23. Further, the release of the hold-down member, the recession of the circular saw, the stoppage of the rotation of the circular saw and the stoppage of the travel of circular saw are made to be done respectively and separately on the basis of the detection signal of the detecting switch, resulting in lowering the percentage of danger due to operational failure.