The present invention provides Hahella chejuensis-derived recombinant cellulase and a use thereof. The recombinant cellulase according to the present invention has a high stability at a high temperature and an optimized activity at a neutral pH, and therefore has a high availability in a process. Also, since the cellulase according to the present invention has an exoglucanase activity as well as an endoglucanase activity, a monosaccharide can be produced during decomposition of cellulose and an additional treatment required in a fermentation process is not needed, and therefore a cost may be reduced. Such an enzyme activity is advantageous to a fermentation or thermal treatment condition for producing a biofuel, and therefore industrial profits may be achieved.