The authors observed in the routine roentgenographic examination, a rare case of Giant cell Reparative Granuloma found in the mandible of woman 23 years of age who had visited Infirmary of Dental College, Seoul National University be cause of the traffic accident. In the serial roentgenograms, authors had obtained the results as follows; 1. Giant cell Reparative Granuloma occurred below the 20 years of age, and occurred in the mandible of female. 2. In roentgenograms, it figures the radiolucent lesion with multilocular appearance. 3. The growing process of Giant Cell Reparative Granuloma is not by the neoplastic reaction but by the local reparative reaction.