PURPOSE: To enable a flashing type electric discharge machining device and an immersion type electric discharge machining device to be properly used with ease as well as to enable a work to be taken in/out efficiently in operation.

CONSTITUTION: A frame shaped working tank installation section 19 is provided for a device main body 1 in order to enclose a work resting bed 5. The working stand side wall member 23 of a bottomless structure is detachably mounted onto the working tank installation section 19 in fluid sealing relation, so that a working tank is thereby formed in the inside of the working tank installation section 19. When the working tank side wall member 23 is mounted on the working tank installation section 19 of the device main body 1, a working tank for immersion type electric discharge machining is formed, and when the working tank side wall member 23 is removed from the working tank installation section 19, working environment is thereby ready for flashing type electric discharge machining.