With the increasing of the elderly population, patients with urinary dysfunction caused by inefficiency of bladder emptying becomes much often than before. However, the current treatments for this kind of bladder dysfunction are limited and unsatisfactory. Low-intensity extracorporeal shockwave therapy (LiESWT) is a very popular emerging treatment in recent years, and abundant of literatures have confirmed that this treatment is safe and effective in myofascial pain and male erectile dysfunction. Recently, many animal experiments have showed that LiESWT could improve urinary dysfunction caused by bladder dysfunction. Taiwan based studies also reported that LiESWT could improve symptoms of overactive bladder. LiESWT is a non-drug, low-invasive and high-safety treatment, which is very suitable for elderly patients. In this study investigator combine the LiESWT and acupuncture to treat the patients with underactive bladder. Investigator hypothesize that LiESWT could improve bladder voiding efficiency.