To verify the superiority of celecoxib (YM177) 200 mg bid to placebo in treatment of patients with low back pain as well as non-inferiority to loxoprofen sodium 60 mg tid.

Inclusion Criteria:

• Patients who have the major site of the low back pain at the 12th thoracic vertebra or lower
• Patients who have had low back pain for at least two weeks

Exclusion Criteria:

• Patients who have a previous history or complication of rheumatoid arthritis, spondylarthrosis with negative serum reaction (ankylosing spondylarthritis, psoriatic arthritis), metastasis of tumor, Paget's disease, fibromyalgia, tumor or infection of spinal cord or intervertebral disc, or any other disease which can cause systemic pain