Considerable research was done to study the fatigue behavior of the reinforced concrete bridge deck which is strengthened by carbon fiber. The purpose of this experimental study is to investigate the fatigue behavior and strengthening effects of the strengthened bridge deck with grid type carbon fiber plastic. The results of this study show that the displacement and the total released energy of strengthened bridge deck are greater than the case of unstrengthened bridge deck. By strengthening of bridge deck, applied load is so distributed on whole deck member that crack concentration is efficiently controled.