For specifying a cause of generation of a water level abnormality alarm in a wire-cut electric discharge machine, stopping supply of a machining liquid to a machining tank when the alarm is generated, draining the liquid; measuring an amount of change in the water level per unit time that is detected by the water level detecting unit; and displaying a question to an operator about the measured amount of change in water level and the state of a water level adjusting mechanism. The operator manually inputs an answer to the displayed question, and specifies, from the answer input by means of the inputting unit, a part which causes the generation of the alarm.