To provide a cutting apparatus which enables a semiplastic body to be smoothly and properly cut by eliminating poor cutting caused by the bending and curling of a cutting wire, through the use of a simple constitution.

This cutting apparatus for the semiplastic body is equipped with a pair of winding drums 2a and 2b with a diameter of 30 mm or more, which are arranged almost in parallel with each other; the cutting wires W, both the ends of which are wound around both the winding drums; driving means 4-8 for rotatively driving both the winding drums; and a tension unit 30 for imparting a prescribed tensile force to each of the wires. Each of the wires W is traveled and moved from one winding drum to the other winding drum in a state wherein the prescribed tensile force is imparted to each of the wires by the tension unit; the semiplastic body P is relatively moved at a prescribed speed with respect to each of the wires, so as to be cut off; and a high-strength fiber is used as the cutting wire W.