A straddle type all terrain vehicle is provided with a chain guide for covering an outer peripheral edge of at least an engaged portion of a driven sprocket with a drive chain from outside in a radial direction inside a chain cover. A rear axle housing is formed with upper and lower flange portions extending upward and downward at opposite end portions in the vehicle width direction of the rear axle housing. The rear axle housing is coupled to a rear end portion of the rear swing arm for swinging forward and rearward about mounted portions of the upper flange portion. The chain cover is mounted on the swing arm side and the chain guide is mounted on the rear axle housing side, respectively.