Provided is a vehicle speed-change system including the following: a transmission; a transmission case that retains the transmission; a shift mechanism that performs a speed-change operation of the transmission; and a shift actuator that operates the shift mechanism. The shift actuator includes the following: a motor; a transmission mechanism that transmits rotation of the motor; and an actuator output shaft that outputs motive power transmitted by the transmission mechanism. The shift actuator is fixed to a side surface of the transmission case, and is arranged such that at least a portion of the motor overlaps the shift mechanism in a side surface view of the vehicle.