To effectively and efficiently wash parts difficult to remove fouling of a crawler traveling part of a vehicle.

Right and left side parts of a frame, and an outer washing device and an inner washing device which are traveled along a track installed in a center void part are provided, a nozzle 25 is provided on the tip of a nozzle tube, and the washing water is sprayed from the inside and the outside toward the crawler traveling part. The nozzle tube 24 in a washing liquid spraying device of the inner washing device is split into a lower tube 24a supported by a nozzle base tube which is turnably supported around the horizontal axis by a supporting body 23 which is commonly used as a liquid feed tube, and an upper tube 24b which is turnable around the longitudinal axis relative to the lower tube, and capable of being fixed to an arbitrary turning position, and a washing liquid spraying device 17 is capable of changing the spraying direction of the nozzle at the tip by adjusting the turning of the upper tube 24b. A nozzle 25 at the tip of the upper tube 24b is rotatably provided around the axis parallel to the turning axis of the nozzle base tube.