A transmission TM comprises a metal V-belt mechanism 20, which is provided between an engine ENG and driving wheels DRW and transmits a rotational driving force from the engine ENG toward the driving wheels DRW with a speed change, and a forward/reverse switching mechanism 30, which includes a planetary gear train and switches the rotational direction between for a forward drive and for a reverse drive and transmits the rotational driving force received from the engine ENG to the metal V-belt mechanism 20. An engine control unit 60 for the transmission TM, while the rotational direction is set for a reverse drive, changes the ratio of the metal V-belt mechanism 20 in the direction where the vehicle speed increases by a predetermined ratio and controls the torque input from the engine ENG such that the torque being transmitted to the driving wheels DRW achieves approximately the same magnitude as that achieved while the rotational direction is set for a forward drive.