The purpose of this study is to evaluate the efficacy and the safety of silodosin in urinary calculi patients.

Inclusion Criteria:

• Patients who have a unilateral ureteral calculus with ≥ 5 mm and ≤ 10 mm at Week 0.
• Patients who are able to visit the site continually as out-patient during the study

Exclusion Criteria:

• Patients who have multiple urethral stones.
• Patients who have or have history of a ureteral stricture or other structural passage obstruction of the ureter on affected side.
• Patients who have been diagnosed with myasthenia gravis, myopathy, spina bifida, spinal cord injury, or fibromyalgia syndrome.
• Patients who have a clinically significant hepatic or renal disorder.
• Patients with postural hypotension or with a history of postural hypotension.
• Patients with a history of sever drug allergy, or patients with a history of hypersensitivity to silodosin.
• Patients who are pregnant, nursing, or desire pregnancy during the study period, or patients who cannot strictly comply with a physician's contraception directions.