To provide an exhaust device of an engine which can improve conditions of an exhaust gas striking a sensor and which can detect an exhaust gas for each cylinder.

In an exhaust device of an engine 1, an exhaust pipe 7 is provided with an upper first concave portion 71a which separates a turbine passage 101 constituting a flow passage of gas discharged from a turbine wheel 21 of a turbo charger 20 from a waste gate passage 102 which constitutes a flow passage of gas discharged from a bypass passage 26 that bypasses the turbine wheel 21 of the turbo charger 20, and a portion positioned at the upstream side and the lower side of an A/F sensor 40 of the waste gate passage 102 is provided with a lower first concave portion 72a formed so as to flow the gas discharged from the bypass passage 26 toward the A/F sensor 40 side.