An apparatus for locking a recliner of a front seat in an automobile comprises a supporting panel installed in a seat frame of a seat back for supporting the back of a passenger. A sliding bar is attached to the supporting panel and moves up and down following a guide bracket installed in both ends of the seat frame. A spring connects the sliding bar to the seat frame in order to enable the sliding bar to move elastically. An upper gear bar is downwardly attached on the lower end of the sliding bar and is provided with gear teeth on the front end thereof. A lower gear bar has gear teeth following the longitudinal direction thereof and connects both ends of the seat cushion frame. The lower gear bar engages with gear teeth of the upper gear bar selectively.