A shift control mechanism is provided for a multiple-forward-speed manual transmission which controls operation of the shift lever between the reverse drive position and one forward drive position to prevent inadvertent shifting which might damage the transmission. A transmission lever whose movement is controlled through the shift lever is formed with a projection extending therefrom which is adapted to engage a movable pin mounted in a housing. The housing is axially movable along a guide shaft and the pin is movable between an extended and a retracted position relative to the housing. The erroneous shifting operation between the reverse drive position and the one forward drive position is prevented by engagement between the projection and the pin in a manner which does not interfere with appropriate shifting of the transmission during vehicle operation.