Recently, "Smart Clothing" technology, along with a rapid change of lifestyle and customers' needs, has been studied and developed for various applications such as Entertainment, Business, and Health Care and Sports areas. Among the number of types in "Smart Clothing" technologies, "Smart Clothing" for health care is anticipated as one of the highly demanded products in future market.The demand of "Smart Clothing" based on bio-medical sensor technology will increase due to the entry of an aging society where a high demand of development in both medical industry and medical welfare rises. This trend is related to the new condition of technological and social transition built through the rapid development of Ubiquitous environment. On the view of customers' demand, "Smart Clothing" technology coincides with the macroflow of customers' general demand on clothing product. In domestic market, however, the research and development of "Smart Clothing" based on a biomedical sensor technology are insufficient. In this research, with a consideration in clothing suitability and prevalence rate, a prototype of "Smart Clothing" is firstly developed for diagnosing basic vital signs of cardiac disorder and respiratory disease. A prototype of smart healthcare clothing developed in this research, maintaining similar appearance to common clothing, is equipped with textile-based sensors and other devices which senses and transmits vital signs, while keeping comfortable fits of clothing. When a person having it on, sensed vital signals are transmitted to computer in hospital through wireless transaction for a real-time monitoring process. It is also designed to send back alarm command to the wearer's cellular phone when emergent condition is detected in his body. The RFID tag, equipped on the inside of "Smart Clothing," stores wearer's medical history and personal data, so that a rescuer can collect the data in emergency case and send them to hospital for faster and efficient treatment for the rescue. An evaluation on usability and comfort of the firstly derived prototype in this research were evaluated. Based on the result from evaluation on the two aspects, the design prototype of sensor-based smart healthcare clothing was revised.