An optical pumping field emission type light-to-current converter is constructed by joining an optical wave guide material (1) through which light is propagated, a conductive transparent film (2), a semiconductor material or an insulating material (3), and a conductor material (4) to each other. The optical wave guide material may have a needle-like shape (6) which is obtained by sharpening the light emission guide side thereof. Thereby is obtained an optical pumping field emission type light-to-current converter having a simplified structure high sensitivity and high-speed response on the order of picoseconds (10 -12 seconds) due to a large field emission current.