A Study of YM178 in Subjects With Symptoms of Overactive Bladder

Inclusion Criteria: * Subjects with symptoms of overactive bladder for at least 12 weeks before the study * Subjects capable of walking to the lavatory without assistance and measuring the urine volume by him/herself * Subject with an average frequency of micturition of 8 or more times per 24-hour period * Subject with an average episode of urgency or urge incontinence of one or more times per 24-hours period * Subject having provided written informed consent by him/herself Exclusion Criteria: * Subject having stress urinary incontinence as a predominant symptom * Subject with transient symptoms suspected for overactive bladder * Subject complicated with urinary tract infection, urinary stones, and/or interstitial cystitis or with a historical condition of recurrent urinary tract infection * Subject complicated with bladder tumor/prostatic tumor or with the historical condition * Subject confirmed to have a post-void residual volume of \>=100ml or with a clinically significant lower urinary tract obstructive disease * Subject with indwelling catheter or practicing intermittent self-catheterization * Subject giving radiotherapy influencing urinary tract functions, or thermotherapy for benign prostatic hyperplasia * Subject giving surgical therapy which may influence urinary tract functions within 24 weeks before the study * Subject with uncontrolled hypertension (indicated by sitting SBP \>=180mmHg or DPB \>= 110mmHg) * Subject with a pulse rate \>= 110bpm or \<50 bpm