Even if an adjustable speed limitation function (ASL) sets a vehicle speed upper limit to a relatively low vehicle speed, a control unit 10 is configured to, in order to suppress the problem of a decrease in fuel efficiency while the ASL is executing the vehicle speed limitation, suppress an output of an engine 2 so that the vehicle speed does not exceed the vehicle speed upper limit, and cause a gear stage of an automatic transmission 3 to be shifted up to a higher speed side gear stage having higher fuel efficiency than a gear stage that is set based on the driving state of a vehicle 1, when a deviation between the vehicle speed detected by a vehicle speed sensor 21 and the vehicle speed upper limit that is set by a vehicle speed upper limit setting switch 24 becomes less than a predetermined threshold.