An exhaust gas treatment device for an exhaust system of an internal combustion engine includes a housing that is adapted to be tied into the exhaust system and at least one exhaust gas purification insert arranged in the housing. The exhaust gas purification insert includes an insert housing which is open at one end and at least one exhaust gas purification element arranged in the insert housing. The housing has at least one insert bracket which has at least one mounting opening on whose opening edge is supported an end section of the insert housing in the form of a ring. The end section forms a first spherical shell segment and the opening edge forms either a second spherical shell segment that is complementary to the first spherical shell segment or a conical jacket segment that fits the first spherical shell segment.