The bioartificial pancreas (BAP), a medical device enclosing insulin-secreting cells in a semipermeable membrane, is expected to physiologically control glucose levels, and thus to be able to inhibit development of serious chronic complications in diabetic patients. In this brief review, we introduce research activities on the development of the BAP in Japan, including membrane preparation for the BAP, evaluation of in vitro and in vivo BAP functions, and challenges for production of insulin-secreting cells from stem cells.