An exhaust system (1) is provided with an exhaust passage that allows exhaust gas discharged from an internal combustion engine to pass therethrough, an exhaust emission control unit including a catalyst (2,3) such as a three-way catalyst (27) to purify the exhaust gas, and an exhaust heat collecting unit that converts thermal energy of the exhaust gas into electric energy. The exhaust passage (25) is formed in the center of the exhaust system provided with the exhaust emission control unit. By-pass passages (26) are formed at both sides of the exhaust passage (25) through which the exhaust gas flows without passing through the exhaust emission control unit. The exhaust heat collecting unit (29) is provided on the outer side of each of the by-pass passages (26).