In inline four cylinder internal combustion engine (1), exhaust ports for a #2 cylinder and a #3 cylinder merge inside cylinder head (3) and form an opening serving as a single collective exhaust port. Exhaust manifold (5) has individual exhaust pipes (6, 7) for #1 and #4 cylinders and collective exhaust pipe (8), and the leading ends of these three exhaust pipes (6, 7, 8) are connected to catalytic converter (11). Exhaust gas introduction angle (θ2) of each of individual exhaust pipes (6, 7) is larger by 30-60 degrees than exhaust gas introduction angle (θ1) of collective exhaust pipe (8). Consequently, flow velocity distribution and temperature distribution in a catalyst carrier become uniform.