Special attention has been paid to introduction of “Optical wiring” in place of conventional “Metallic wiring” in Printed Wiring Board level. High efficiency and alignment-free coupling between optical wirings and optical devices is a key in this field. This paper introduces a new optical interface applying “Optical pin” which has an analogy to electrical pins widely used in present electronics boards. Concept of optical pin enabling 90-deg optical path conversion is proposed and a preliminary experiment using a fiber optical pin is introduced. Then a micro optical pin fabricated by Self-Written Waveguide Technology using UV-curable resin is shown.