EDM machining fluid filtration device

A seal (15) is brought into contact with a filter media (F1), a filter pump (P2) is operated to start filtration, and a signal from a pressure sensor (25) is received. When a predetermined value is exceeded by the signal from the pressure sensor (25) , the filter pump (P2) is stopped, the seal (15) is separated from the filter media (F1), and take-up of one section of the filter by a filter collection roll (11b) is started. In finishing filter supply from a filter supply roll (11a), drive of a motor (11a) is stopped, and an alarm signal is transmitted. If the supply is not to be finished, one section of the filter (F1) is taken up by the filter collection roll (11b), and the next stage of filtration is entered.