A power transmission system that includes a torque converter; a transmission having a planetary gear; a case configured to accommodate the torque converter and the transmission; a support having a wall that is fixed to the case between the torque converter and the transmission and a tube that extends in an axial direction from an inner circumferential portion of the wall; a stator shaft that is connected to a stator of the torque converter via a one-way clutch; and a tubular connector that connects the support and a stationary element of the planetary gear together.