The present invention relates to an exhaust gas treatment device for an exhaust system of an internal combustion engine, more preferably of a road vehicle with a housing, in which at least one exhaust gas treatment element is arranged and mounted by means of a bearing mat and with an outlet pipe which is fluidically connected to an outlet chamber formed in the housing. The risk of a contamination of the bearing mat with water can be reduced with a separating bottom which is arranged in the housing and separates the outlet chamber from a collecting chamber. The separating bottom includes several passage openings through which the outlet chamber is fluidically connected to the collecting chamber and which are each enclosed by a collar protruding into the outlet chamber.