An exhaust pipe of an engine includes a crank-shaped pipe portion having a first bend and a second bend which guide exhaust gas to a mixer, and a straight pipe portion which is continuous with the second bend. The mixer is arranged in the straight pipe portion. An injector is attached to a portion of the second bend which faces the mixer. The injector has an injection axis which extends in a longitudinal direction of the straight pipe portion so as to point toward the mixer. A guide which guides a part of the exhaust gas from the first bend toward the injector is provided inside the crank-shaped pipe portion.