A track-traveling four-wheel vehicle is arranged such that pedalling power of a passenger is transmitted to rear wheels as drive wheels through a chain, and the rear wheels and front wheels as driven wheels roll along two rails. The vehicle has: frames constituting a rectangular body; a swing frame arranged such that an L-shaped end portion is pivotally mounted in the middle portion of the rear frame through a vertical shaft and the other L-shaped end portion extends along the longitudinal direction of the body, the swing frame being supported to swing in a horizontal plane; and a driven wheel support frame pivotally supported at the distal end portion of said swing frame. The front frame is slidably supported in the vicinity of the distal end portion of the swing frame through a sliding support mechanism.