Abstract: An optical module having a simple construction and excellent wear resistance that can be manufactured at low cost and high accuracy, and a method of manufacturing the same. The optical module has such a construction that an optical semiconductor element (10), a holder (14) for holding it, and a receptacle core (16) for holding a ferrule of an optical plug being connected in a fixedly fitted manner are provided, so that the optical semiconductor element is optically coupled with an optical fiber in the ferrule when connecting the optical plug. The receptacle core is an integrally formed metallic tubular piece having a high hardness film (16a) of TiC formed at least on the inner circumferential surface of the bore thereof, and a ferrule stopper (18) is provided at the proximal end of the bore. The holder and the receptacle core may be of an integrally formed construction. The high hardness film is formed into a thickness of 1-10 .mu.m with the CVD process.