To provide a cutting device which can make a shortest distance between the tip face and the cut face of a wood almost the same constantly regardless of a change in the cutting angle.

In the cutting device, a positioning part 90 for setting a position for the end part of a wood is of a cam-like member type and the position for the end part of the wood is changed by the rotating angle of the member. In addition, a circular saw support part 30 which supports a motor-driven circular saw 40 in a freely rotating manner is connected to the positioning part 90 with the help of a connecting member 100. Consequently, when the motor- driven circular saw 30 is rotated to move in order to change the cutting angle, the positioning part 90 is interlocked to rotate. Thus it is possible to change the position for the end part of the wood determined by the positioning part 90 in compliance with the change of the cutting angle. Therefore, the wood can be cut to the almost constant length regardless of the variations of the cutting angle.