Exhaust purification apparatus

Even when an exhaust gas (3) is inverted and then introduced in a post-treatment unit of selective reduction catalyst (6), etc., the introduction in the post-treatment unit can be conducted under the uniformized flow distribution of the exhaust gas (3). There is disclosed an exhaust purification apparatus having an exhaust system provided with a selective reduction catalyst (6) (post-treatment unit) adapted to allow passage of an exhaust gas (3) and purify the same and employing a layout for inverting and then introducing the exhaust gas (3) in the selective reduction catalyst (6). The apparatus has an introduction part (14) covering the entrance side end face of the selective reduction catalyst (6), adapted to introduce the exhaust gas (3) via exhaust introduction port (13) from a direction approximately orthogonal to the axial center direction of the selective reduction catalyst (6). The introduction part (14) is provided with a recessed part (15) (first recessed part) curved toward a direction departing fr