An exhaust gas purification apparatus in which layout restriction is lessened to be able to further achieve space-saving is proposed. The exhaust gas purification apparatus includes a first cylindrical housing in which an oxidation catalytic converter and a PM collection filter are contained and a second cylindrical housing in which a reducing catalytic converter and an ammonia oxidation catalytic converter are contained. The exhaust gas purification apparatus further includes a communicating pipe that connects between far end portions of both the housings, and a nozzle that is disposed in the communicating pipe and injects liquid reducing agent in exhaust gas. The two housings are closely disposed such that axis lines thereof are arranged substantially parallel. The communicating pipe is disposed such that an axis line thereof is arranged substantially parallel with the axis lines of the housings. A flow passage of the exhaust gas from the first housing through the communicating pipe to the second housing is formed into a substantial N-shape.