A wire electrical discharge machine for performing electrical discharge machining on a workpiece to be machined in a working fluid of deionized water, comprising: a filter configured to remove machined swarf produced by electrical discharge machining from the working fluid; characterized in that the wire electrical discharge machine comprises: a heating device (66, 66A) configured to heat the working fluid stored inside the filter up to, at least, a predetermined temperature (Tm) at which magnesium contained in the machined swarf in the working fluid changes to magnesium hydroxide; and a control device configured to actuate the heating device (66, 66A) using a predetermined condition as a trigger and stop the operation of the heating device (66, 66A) to terminate heating of the working fluid, wherein: the control device is configured to stop the operation of the heating device (66, 66A) to terminate heating of the working fluid when a predetermined time (Ti) required for the working fluid to reach, at least, the predetermined temperature (Tm) elapses from start of heating, or the wire electrical discharge machine further comprises a temperature detector configured to detect a temperature of the working fluid and the control device is configured to stop the operation of the heating device (66, 66A) to terminate heating of the working fluid when the temperature of the working fluid reaches the predetermined temperature (Tm) or higher. characterized in that the wire electrical discharge machine comprises: a heating device (66, 66A) configured to heat the working fluid stored inside the filter up to, at least, a predetermined temperature (Tm) at which magnesium contained in the machined swarf in the working fluid changes to magnesium hydroxide; and a control device configured to actuate the heating device (66, 66A) using a predetermined condition as a trigger and stop the operation of the heating device (66, 66A) to terminate heating of the working fluid, a heating device (66, 66A) configured to heat the working fluid stored inside the filter up to, at least, a predetermined temperature (Tm) at which magnesium contained in the machined swarf in the working fluid changes to magnesium hydroxide; and a control device configured to actuate the heating device (66, 66A) using a predetermined condition as a trigger and stop the operation of the heating device (66, 66A) to terminate heating of the working fluid, wherein: the control device is configured to stop the operation of the heating device (66, 66A) to terminate heating of the working fluid when a predetermined time (Ti) required for the working fluid to reach, at least, the predetermined temperature (Tm) elapses from start of heating, or the wire electrical discharge machine further comprises a temperature detector configured to detect a temperature of the working fluid and the control device is configured to stop the operation of the heating device (66, 66A) to terminate heating of the working fluid when the temperature of the working fluid reaches the predetermined temperature (Tm) or higher. the control device is configured to stop the operation of the heating device (66, 66A) to terminate heating of the working fluid when a predetermined time (Ti) required for the working fluid to reach, at least, the predetermined temperature (Tm) elapses from start of heating, or the wire electrical discharge machine further comprises a temperature detector configured to detect a temperature of the working fluid and the control device is configured to stop the operation of the heating device (66, 66A) to terminate heating of the working fluid when the temperature of the working fluid reaches the predetermined temperature (Tm) or higher.