Abstract: In an oil passage structure in a rotary shaft, including two systems of oil passages different in pressure that are provided extending from both ends of the shaft, the rotary shaft is provided with oil supply holes in the radial direction of the shaft for connection between a center hole in the shaft and locations to be supplied with oil. The oil supply holes are bored from the outside of the shaft. At this time, burrs are generated at end portions of the oil supply holes on the side fronting on the center hole. Where the depth of the shaft center hole is a dead end, removal of the burrs is not easy. The shaft center hole is used as an oil passage wherein burrs, if any, in the hole can be easily removed. The two oil passages are in communication with each other through a communication passage smaller than the oil passages in diameter. The smaller-diameter communication passage is closed by pressing a steel ball therein, thereby making both of the oil passages independent from each other.