Nowadays, many kinds of life-supporting robots are currently being developed for a wide range of users, particularly the elderly; however, to enhance their performance, such robots have inescapably become large and heavy. Unfortunately, their huge size and weight are factors invoking a sense of fear in users (mental reason) and hindering users' daily activities inside their small house (physical reason). To spread of the use of life-supporting robots into standard Japanese homes, we therefore created two types of compact and lightweight buoyancy-based mobile balloon robots. The first is a balloon walking robot that can provide humorous and slow movements on two legs for younger sedentary children. The other is a balloon jumping robot that can move around the house for active children and elderly users. Based on the results of the previous questionnaire survey, we composed the two prototype robots using a balloon filled with helium and motion mechanisms. In this paper, we show the design concepts, mechanisms, and properties of these new life-supporting balloon-mobile robots. In addition, a field study conducted in both a nursery school and a care facility has shown that these robots have significant potential for use as communication and therapy robots in terms of their attractive appearance and feather-like motion.