A method of ferrules used in an optical connector for connection and short-circuit of making multichannel optical signals. Heretofore, many fiber receiving holes have been arranged along a line at regular intervals with tolerance amounting to less than 1 micron. 10 and connect two ferrules, a precisely processed cylindrical metal guide pin under 1 micron, precise pitches formed in ferrules and a metal pin guide hole are used, Consequently, it has been necessary to maintain a high degree of precision. The present invention maintains a high degree of precision by reverse direction connection dependent merely on a predetermined height a reference plane. The reference plane is formed by relatively easy plane processing as the method of maintaining precise height and directivity of flow is added to the inside of a mold.