An exhaust gas-treating device (1) for an exhaust system of an internal combustion engine, especially of a motor vehicle, has a housing (2), which has a jacket (3) extending circumferentially on the side and two end-side end bottoms (4, 5). Maintenance is simplified with at least one mounting tube (6), which passes through one or the first end bottom (4) and into the outlet end (8) of which a particle filter (7) is plugged axially from the outside, with a deflecting housing (9). The deflecting housing (9) contains a deflecting chamber (10), and has at least one inlet (11) communicating with the deflecting chamber (10) and at least one outlet (12) communicating with the deflecting chamber (10). A fastening device (13) is provided for detachably fastening the respective inlet (11) at the respective outlet end (8) of the mounting tube (6).