Inclusion Criteria:

1. Patients who are 20 years old or over with overactive bladder
2. Total number of urinary incontinence episodes per week is 5 or over
3. Mean number of micturition per day is 8 or over
4. Mean number of urinary urgency episodes per day is 1 or over
5. Other inclusion criteria as specified in the study protocol

Exclusion Criteria:

1. Patients with genuine stress incontinence
2. Patients suffering from complications such as bladder tumor, bladder stone and urinary tract infection
3. Patients who have undergone surgical operation of urinary and/or genital organs within 6 months prior to the study
4. Patients suffering from complications for which anticholinergics are contraindicated
5. Other exlcusion criteria as specified in the study protocol