To develop and provide exhaust pipe structure of a self-traveling working machine improved to prevent or minimize degradation in visibility from an operation part caused by an exhaust pipe in which an exhaust treatment device is installed, while the exhaust treatment device for cleaning exhaust gas is installed to the exhaust pipe vertically arranged to a side of a front portion of the operation part.

In the exhaust pipe structure of a self-traveling machine, the exhaust pipe 5 is arranged vertically to the side of the front portion of the operation part arranged in the rear of an engine hood. The inside of the exhaust pipe 5 is vertically partitioned into a pair of exhaust conduits 9 in parallel with each other, and each of the exhaust conduit 9 is provided with the exhaust treatment device B. Each exhaust conduit 9 is formed of an expanded conduit part 9A with large cross-sectional area in which the exhaust treatment device B is installed, and a connection conduit part B with small cross-sectional area communicating therewith. A pair of expanded conduit parts 9A are vertically-separated from each other, and are arranged in series in such a state where they are overlapped with a viewing direction P connecting the operation part with the exhaust pipe 5 when seen from a vertical view.