To provide a wire saw device and a method for cutting by a wire saw capable of improving a quality level of a machined surface and preventing a crack and fall thereof by eliminating an influence of pressure of a coolant liquid.

The wire saw device 1 cuts a work material X by pressing the work material X against a traveling wire 3 while showering a coolant liquid C, and soaks the cut work material X in a water tank 5 which receives the coolant liquid C. In the water tank there are provided partition walls 8a, 8b ahead of and at the back of the work material X in the traveling direction of the wire 3.