There is provided a running device for track-laying vehicle, which can resolve a feeling of fear of falling height in a leading end portion of a crawler while relax a large impact when the crawler runs over a raised contact area. The running device includes a spring constant equalizing unit that equalizes an apparent spring constant of a second arm of lower track roller bogie device over a total length. The apparent spring constant is generated in maximum reverse camber of the crawler. The spring constant equalizing unit increases an oscillation angle α of the second arm that can abut on the first arm in the maximum reverse camber of the crawler such that the oscillation angle α of the second arm is larger than a crossing angle β of the connecting link. Desirably the increased maximum oscillation angle of the second arm is 1.3-2.0 times the crossing angle β.