PURPOSE: To aim at shortening the time required for machining preparations, by installing each of machining solutions different in a specified resistive value alone separately, while constituting a device so as to make each machining solution feedable in a separate manner.

CONSTITUTION: A used foil solution 4 is stored in a cleaner tank 1 or 1' by way of a pump 7 and a filter 5. The cleaner tank is constituted of the cleaner tank 1 storing a clean solution 3 being high in a specific resistive value and another cleaner tank 1' storing a clean solution 3' being low in the specific resistive value. And, each of hoses 12W14 and 16 is shifted to some extent at need whereby the clean solution 3 being high in the specific resistive value and the clean solution 3' being low in the said value are properly used at discretion. With this constitution, the setting time of the machining solution's specific resistive value is shortened, thus the time required for machining preparations is well promotable for reduction.