PURPOSE: To efficiently remove the contaminant bonded to the outer surface of a filter in a laborsaving manner by supplying a washing soln. to the inside of the filter to discharge the same to the outside and ejecting the washing soln. to the outer surface of the filter rotated on a work turntable.

CONSTITUTION: A work turntable 4 is provided in a washing chamber 3 in a rotatable manner and a contaminated filter 1 is arranged on the work turntable 4. A washing soln. 2 of a glycol ether type detergent is circulated by a pump 6 to be supplied to the inside of the filter 1 to be discharged to the outside while the spray of the washing soln. 2 is ejected on the outer surface of the rotated filter 1 from a spray nozzle 8. By this constitution, the contaminant bonded to the filter is efficiently removed without relying on labor.