PROBLEM TO BE SOLVED: To provide a wire electric discharge machine, uniformly keeping the machining fluid temperature in a machining vessel even when the machining state is changed to roughening, finishing and so on. SOLUTION: A first temperature sensor S1 for detecting the working fluid temperature in a fresh water vessel 4 is provided in the fresh water vessel or a working fluid cooling device 6. A second temperature sensor S2 for detecting the machining fluid temperature in the machining vessel 2 is provided. A control device of the wire electric discharge machine selects the second temperature sensor in machining with a large heating value such as roughening and selects the first temperature sensor S1 in machining with a small heating value such as finishing depending on the machining condition. The machining fluid cooling device 6 controls the machining fluid in the fresh water vessel 4 to be cooled based on the temperature detected by the selected temperature sensor. Even if the machining condition is changed, the machining fluid temperature in the machining vessel can be kept uniform to a temperature near the target temperature, and also in finishing, a temperature change can be made smaller. Since the machining fluid temperature can be kept uniform, high machining accuracy can be obtained. COPYRIGHT: (C)2008,JPO&INPIT