An exhaust gas treatment device (1) for an exhaust system of an internal combustion engine, especially of a motor vehicle, has a multipart housing (2), which contains an oxidation-type catalytic converter unit (5) and, downstream therefrom, a particle filter unit (6) one after another in an axial direction extending in parallel to a longitudinal direction (3) of the housing. The housing (2) contains an inlet housing part (7), which has an exhaust gas inlet (8) and the oxidation-type catalytic converter unit (5), and an outlet housing part (9), which has an exhaust gas outlet (10) and into which the particle filter unit (6) axially protrudes. The maintenance of the exhaust gas treatment device is simplified if at least two housing parts (7, 9, 12) axially adjoining each other are detachably connected to one another by means of a clamp connection (11) and if at least one bracket (13) is provided, which is axially rigid in relation to the particle filter unit (6) and which cooperates with at least one such clamp connection (11), such that the bracket (13) is axially fixed at least one housing part (7, 9, 12) by means of the respective clamp connection (11).