Osteoblastoma is a rare benign bone-forming tumor and is characterized histologically by pure osteoid and woven boneproduction, not lamellar bone production in a highly vascular matrix. The legion is similar to osteoid osteoma histologically and must be distinguished from osteosarcoma. This tumor affects young people between 10 and 30 years of age. Males are affected 2 times more frequently than females. We have experienced a case of benign osteoblastoma of the articular process of the lumbar spine in a 21-year old male, and treated the case by en-bloc resection of tumor mass and posterior fusion with autogenous bone graft, and confirmed by histological examination.