PURPOSE: To execute clean washing without reverse contamination by supplying successively a solvent filtered and purified separately by a main tank system and a new liquid tank system, to a washing tank.

CONSTITUTION: A main tank system and a new liquid tank system are formed by connecting a washing tank 1 and a solvent tank 2 constituted of a main tank 2A and a new liquid tank 2B through a drainage valve 3 and a button trap 4, connecting the solvent tank 2, the button trap 4 and a solvent pump 5 through a three-way valve 6, and connecting the solvent pump 5 and the washing tank 1 through an outflow valve 7 and a filter 8. Also, by connecting the solvent pump 5 and the new liquid tank 2B through an inflow valve 9, a distiller 11, a cooler 12, a moisture separator 13 and a water absorbing tank 14, a distiller system is formed together with the main tank 2A and the three- way valve 6. In such a state, the solvent is supplied successively from the main tank system in a first bath, and from the new liquid tank system in a second bath, and reproduced by the distiller system. In such a way, reverse contamination does not occur, and clean washing can be executed.