Recently, the attention has been focused on developing a wearable power assist robot by installing an actuator, such as motors, in the body and assisting and enhancing muscular power; there has been a considerable increase in research and development in some institutes and companies worldwide. Various types of wearable power assist robots have been proposed to support the upper and lower limbs, waist, and so on, which are to be used for the operational support of elderly and disabled people, nursing care work, and heavy lifting work in production sites. Some of them have been commercialized and their promotions have been advanced. Their social needs are extremely high, and there is an expectation of further improvements of assisting effect, installation performance, safety and convenience and affordability. In this paper, after the current state of research and development of this kind of robot is outlined, and our researches on pneumatic rubber artificial muscles, exoskeleton type standing motion assist devices, and wearable, lightweight, and soft power assist robots without an exoskeleton are introduced.