To facilitate maintenance work by simplifying a structure, reduce a load on running wires, and make a cutting face flat and smooth in a cutting device which, when, for example, an autoclaved lightweight concrete (ALC) panel is manufactured, is used for cutting a semiplastic body, such as the uncured ALC, into a panel shape or other required shape.

The semiplastic body cutting device relatively moves the cutting wires disposed in a tension state, and a semiplastic body, such as un uncured ALC, thereby cutting the semiplastic body into a required size and shape. A plurality of pairs of front and rear wires W1 and W2 which are disposed at the front and rear in the direction of movement relative to the semiplastic body F and cut the same area of the semiplastic body, are arranged side by side in a direction crossing the relative movement direction. Each front wire W1 is disposed and fixed in a tension state in a predetermined position and each rear wire W2 is made to continuously run and move in the longitudinal direction of the wire until one cutting operation finishes when the semiplastic body is cut.