A filter assembly of a washer is disclosed, by which particles contained in water can be efficiently filtered off in the course of washing the laundry and by which the filtered-off particles are prevented from being discharged from the filter assembly. In a washer including an inner wall having an outlet and a circulation passage provided between the inner wall and a wash tub to enable water to circulate to the outlet from a bottom of the wash tub, the present invention includes a closed-type filter unit configured to filter off particles from the water discharged from the outlet and to prevent the filtered-off particles from being externally discharged.