A case of lumbar facet joint infection associated with epidural and paraspinal abscess is presented. A 57-year-old man was hospitalized with severe low back pain that radiated into the bilateral buttocks and legs. The patient had a temperature of 37.3 degrees C, and the biochemical inflammatory parameters were elevated. Initially on admission, we administered antibiotics intravenously. However, pain increased, fever elevated gradually, and bladder-bowel disturbance appeared. Magnetic resonance imaging (MRI) showed effusion in the widened facet joint, paraspinal muscles, and epidural space, which compressed the theca severely. We performed an immediate surgical debridement combined with thorough antibiotic therapy and achieved excellent results. MRI was useful for precise diagnosis and operative planning.