To provide a regeneration means of a filter including ash removing for capturing particle-like matter in exhaust gas emitted from an internal combustion engine.

A filter backwash device 10 is equipped with a backwash chamber 25 which has an opening and can be mounted facing the opening to a filter processing side of the filter 1, a backwash air supply means 21, and a backwash valve 13 provided in a piping system 19 connecting the backwash chamber 25 to the backwash air supply means 21. The filter backwash method is provided where the backwash air is supplied to the filtering side of the filter 1 with the filter backwash device 10 through the backwash valve 13 and discharged from the gas supply side of the filter 1 through the filter 1. In this case, a relation Cv × P/A > 0.6 is satisfied, wherein A (m2) is the filtering area of the filter 1, Cv is the value of Cv of the backwash valve 13, and P (MPa) is the pressure of the backwash air.