To provide a circular saw device for cutting capable of highly accurately cutting a workpiece, by easily setting the workpiece by an industrial robot by opening an upper part of a set position of the workpiece.

An inclined base 2 is fixed on a stand in an inclined state, and a clamp device 9 for clamping the workpiece is arranged on the lowest end part of the lowest position of an inclined base upper surface. Two sliding rails 3 are laid in the inclined direction on the inclined base, and a movable carriage 5 is movably installed in the inclined direction on the sliding rails via a slider 4. A circular saw shaft 11 of a circular saw unit 10 is rotatingly drivably journaled on the movable carriage by being linked to a motor in the right-angled direction to the sliding rails. A circular saw 13 is fixed to the tip of the circular saw shaft 11, and a ball screw 6 is rotatably supported along the sliding rails on the inclined base 2, and a female screw 6b for threadedly engaging with the ball screw 6 is fixed to the movable carriage 5.