A control device for controlling engagement of desired gears of a gearbox. The control device includes a holder unit and at least one control rod which has a relating locking arrangement and is arranged for linear movement in the holder unit. The control rod is provided with one or more recesses which each define a predetermined setting position of the control rod relative to the holder unit. The locking arrangement includes a locking device which is movable, substantially perpendicularly to the control rod's longitudinal axis, between a first position in which the locking device engages in one of the recesses in the control rod, and a second position in which the locking device does not engage in any of the recesses in the control rod. A wire spring fastened in a holder arrangement is firmly connected to the holder unit. The locking device is mounted on or forms part of the wire spring and is movable from the first position to the second position against the action of the spring force of the wire spring. A gearbox comprising such a control device is disclosed.