The present invention provides a method of resuming operation of a wire saw in which slicing of a workpiece is suspended and then resumed, including slicing the workpiece while detecting a traveling direction and a traveling speed of the reciprocating wire and recording them chronologically; and resuming the slicing while controlling the traveling direction and a traveling time in the traveling direction of the wire on a basis of a wire traveling history recorded until the suspending of the slicing of the workpiece such that the reciprocating cycle of the wire becomes continuous between before the suspending and after the resuming of the slicing of the workpiece. This method enables the slicing to be completed while the nanotopography of the sliced wafer is surely prevented from degrading, even when the slicing of the workpiece with a wire saw is suspended due to, for example, breaking of the wire.