Wire saw and method for driving wire saw

In a wire saw, an object to be processed is pressed against a wire (10), whereby the object to be processed is cut. This wire saw is provided with a first bobbin (11) having a wire reel surface on which the wire (10) is reeled before the wire (10) is used in cutting, a second bobbin (12) having a wire reel surface on which the wire recovered from the first bobbin (11) is reeled, and a rotation control unit (60) for controlling the rotation of the first bobbin (11) and the rotation of the second bobbin (12). The first bobbin (11) and/or the second bobbin (12) includes a bobbin body (40, 50) to which the wire reel surface is provided, and a cover (42, 52) to which is provided a cylindrical winding surface that surrounds the wire reel surface. The first bobbin (11) and the second bobbin (12) are controlled such that when the wire (10) moves in a reciprocating manner therebetween, the wire (10) is wound on the winding surface.