In May 2003, establishment of human embryonic stem (ES) cell lines was reported in Japan, demonstrating that a new era of research on regenerative medicine had begun in Japan. Considering that stem cells, including ES cells, can be differentiated into various types of cells, regeneration of organs is expected. The population of stem cells is not enough for use in clinical therapy, so it is necessary to expand them in vitro. Animal-derived growth-supporting cells are generally required for the expansion. However, these non-human animal cells are not suitable because of potential cross-contamination with pathogens such as viruses or prions derived from animals. Therefore, development of an artificial substrate mimicking the cell-growing environment in place of the supporting cells is desired for use in regenerative medicine. Here, the design of a substrate surface for culture of stem cells is discussed.