A vehicle planetary gear device includes a ring gear, a sun gear, and a carrier, and pinions housed in the carrier. A penetration hole formed in a hollow cylindrical portion of the carrier has two inner wall surfaces that face an outer peripheral surface of a pinion. One of the inner wall surfaces has a curvature radius larger than the radius of the pinion, and has a curvature center that is apart from the radius center of the pinion gear. The pinion is disposed with respect to the carrier with a predetermined space formed between the one of the inner wall surfaces and the outer peripheral surface of the pinion, and thereby slides along a radial direction of the carrier.