Abstract :Transdermal drug delivery has many advantages, such as drugs can escape from first-pass effect of liver, non-invasive administration and so on. Moreover, maintenance of prolonged plasma concentration of drugs is considered to be possible. Side effect caused by the rapid increase in plasma concentration is possibly prevented by transdermal administration of drugs. Breaking of administration is easy and frequent administration is needless. Those properties of transdermal drug delivery contribute increase in adherence and QOL.