In order to enable the future construction of molecular devices made of functional proteins, we have developed a technique for microimmobilization of proteins into organized patterns on a silicon wafer. A specific binding reaction between streptavidin and biotin forms the basis of our method. Active and inactive biotin regions were created on a silicon wafer using a photolithographic technique. Circuit-type patterns and 0.75/1.5 mu m line-and-space patterns of a model fluorescent protein, B-phycoerythrin, were successfully created on a silicon wafer.