A vehicle drive device comprising: a rotating electrical machine serving as a drive power source for a first wheel and a second wheel; a differential gear device that distributes drive power from the rotating electrical machine to the first wheel and the second wheel; a reduction device including a planetary gear mechanism (31, 32) including a sun gear (S31, S32), a carrier (C31, C32), and a ring gear (R31, R32); and a case that accommodates the rotating electrical machine, the differential gear device, and the reduction device, wherein the differential gear device and the reduction device are disposed coaxially with the rotating electrical machine, the reduction device is disposed between the rotating electrical machine and the differential gear device in an axial direction, the reduction device further includes a second planetary gear mechanism including a second sun gear, a second carrier, and a second ring gear, in addition to a first planetary gear mechanism including a first sun gear, a first carrier, and a first ring gear, the first planetary gear mechanism being the planetary gear mechanism, the first sun gear being the sun gear, the first carrier being the carrier, and the first ring gear being the ring gear, the first planetary gear mechanism is disposed more on the rotating electrical machine side in the axial direction than the second planetary gear mechanism, a supporting member (9, 109, 209, 309) disposed inside the case is supported by the case and rotatably supports the second carrier, both the first ring gear and the second ring gear are unrotatably supported by the supporting member (9, 109, 209, 309), the case and the supporting member (9, 109, 209, 309) are in plane contact with each other, a contact surface (11sa, 11sb, 12s, 91as, 191as, 192as, 291as, 292as, 391as, 392as) between the case and the supporting member (9, 109, 209, 309) lies in a direction orthogonal to the axial direction. a rotating electrical machine serving as a drive power source for a first wheel and a second wheel; a differential gear device that distributes drive power from the rotating electrical machine to the first wheel and the second wheel; a reduction device including a planetary gear mechanism (31, 32) including a sun gear (S31, S32), a carrier (C31, C32), and a ring gear (R31, R32); and a case that accommodates the rotating electrical machine, the differential gear device, and the reduction device, wherein the differential gear device and the reduction device are disposed coaxially with the rotating electrical machine, the reduction device is disposed between the rotating electrical machine and the differential gear device in an axial direction, the reduction device further includes a second planetary gear mechanism including a second sun gear, a second carrier, and a second ring gear, in addition to a first planetary gear mechanism including a first sun gear, a first carrier, and a first ring gear, the first planetary gear mechanism being the planetary gear mechanism, the first sun gear being the sun gear, the first carrier being the carrier, and the first ring gear being the ring gear, the first planetary gear mechanism is disposed more on the rotating electrical machine side in the axial direction than the second planetary gear mechanism, a supporting member (9, 109, 209, 309) disposed inside the case is supported by the case and rotatably supports the second carrier, both the first ring gear and the second ring gear are unrotatably supported by the supporting member (9, 109, 209, 309), the case and the supporting member (9, 109, 209, 309) are in plane contact with each other, a contact surface (11sa, 11sb, 12s, 91as, 191as, 192as, 291as, 292as, 391as, 392as) between the case and the supporting member (9, 109, 209, 309) lies in a direction orthogonal to the axial direction.