Being small is a major virtue for medical devices, which enables low-invasive surgery and long-term treatment and/or monitoring by being attached or implanted to the patients. Hence, micro/nano medical devices, which have been developed via micro/nano technologies, are absolutely promising. The author's group also has worked on several micro/nano medical devices, which include implantable artificial kidney and needle-type dry electrodes for electroencephalogram (EEG) measurement. Both devices exploit micro/nano technologies to exhibit unique characteristics. Though they are still preliminary, through the research, we found that “Jisso” technologies are mandatory. Jisso originates from a Japanese word whose meaning include wiring, sealing, packaging, and even system implementation. Jisso technologies are the technologies which can make the micro/nano medical devices truly practical. In this presentation, I would like to share the idea of Jisso technologies for micro/nano medical devices using the artificial kidney and the needle-type EEG dry electrodes as the examples.