In an exhaust gas purification apparatus provided in an exhaust as path of an engine, it is an object of the present invention to shorten a pipe length of a bypass path bypassing a purification catalyst as short as possible, thereby reducing initial costs. The exhaust gas purification apparatus includes a purification casing in which at least the purification catalyst is accommodated. The purification catalyst purifies exhaust gas from the engine. The purification casing is integrally provided with the bypass path separately from the purification path in which the purification catalyst exists. The bypass path makes the exhaust gas bypasses the purification catalyst without passing through the purification catalyst.