To provide a filter washing device which makes a detergent aqueous solution such as soap water permeate all fine exhaust gas passages formed in the porous partition wall of a filter and washes the filter by peeling off PM and ashes adherent to the partition wall from the partition wall and a filter washing method.

The filter washing device removes particulate materials caught by the filter 3 and ashes accumulated on the filter from the filter 3 by using the detergent aqueous solution S and high pressure fluid. The device is equipped with a turn table 7 which is installed in a filter washing device main body and on which the filter 3 is mounted rotatably, rotation driving means 8 and 8a which rotate/drive the rotary shaft 9 of the turn table 7, a jet nozzle 13 which is set above the filter 3 mounted on the turn table 7 and ejects the high pressure fluid, and reciprocating drive means 12, 12a, and 12b for reciprocating/driving the jet nozzle 13 above the filter 3 along a surface crossing the rotation center axis L1 of the turn table 7.