To provide a cutting device capable of cutting a work object composed of a single member or a composite member by a single tool and improving the service life and reliability.

First and second rotary units 110 and 120 have a pair of oppositely arranged rotary bodies 111 and 121 and stroke bodies 130 and 140 rotatably installed on support shafts 113 and 123 installed between the rotary bodies. The stroke bodies 130 and 140 have prescribed fitting clearance to the support shafts, and are installed so that a part of the outer periphery of the stroke bodies can be positioned outside the outer periphery of the rotary bodies. The first and second rotary units cut the work object by colliding the stroke bodies in order with the work object while rotating at a high speed. The cutout depth by the stroke body of the second rotary unit is larger than the cutout depth by the stroke body of the first rotary unit, and the stroke body of at least the single rotary unit collides with the work object at a speed not less than a critical impact speed.