A Study to Evaluate Efficacy of 『Opast Tablet』for Neurologic Claudication in Patients With Lumbar Spinal Stenosis

Inclusion Criteria: * Subject is fully understand the clinical trial and obtained informed consent. * Age 20-75years. * Patients with a confirmed diagnosis of waist of spinal canal stenosis. * Limb pain caused by waist of spinal canal stenosis index of VAS 3 or more patients. * Subject who has numbness symptom on lower extremity(ies) and intermittent claudication that are due to spinal canal stenosis and fulfills both of following criteria at the same time * When screening visit, a medical examination by interview had the following symptoms in subjects ; In daily life walking, when walked by within 20 minutes on flatland, the subject can feel the symptoms (numbness, pain or tightness on lower extremity(ies), etc.) * Subject who experienced numbness, pain, tightness or other similar symptom(s) on lower extremity within 15 minutes from test start at baseline(D1) evaluation. * speed: 3km/hr, grade:0%, posture: should keep their lumbar spinal extended Exclusion Criteria: * Pregnant or lactating women of childbearing potential not employing adequate contraception. * Patients who have the hereditary problem of galactose intolerance, Lapp lactase deficiency or grape sugar-galactose absorption defect. * Patients with systemic disease affecting the lower limbs. * Patients who have cauda equina syndrome. * Patients with acute osteoporosis compression fracture in lumbar vertebra. * Patients who have gait disturbance of degenerative arthritis by hip joint, knee joint, ankle joint. * At least one month before the start of the study, patients use of steroid drug except lumbar dura mater. * 6 month before the start of the study, patients with ischaemic disease in blood vessel, lung or the coronary artery, varicose artery. * Patients with lumbar necrosis in head of femur avascular necrosis, necrotic foot ulcer. * Patients surgery by lumbar fusion and lumbar decompression. * Patients with renal disease or need to hemodialysis. * serum creatinine \> 2xUNL * 3 month before the start of the study, patients participated in another clinical research. * Patients with difficult understanding spirit incompetence, lack of will or language barrier. * The investigator judged seriously ill patients need surgery patient.