A twin-core ferrule structure is provided which is miniaturized in size, facilitated for accurate positioning the optical axes of two optical fibers, and improved both in degree of freedom of determining a shape and in high-volume productivity. The twin-core ferrule 21 comprises a cylindrical sleeve 22 having a first optical fiber element fitting hole 23 provided in the front region of a circular cylindrical body thereof to extend along the center axis of the same, a second optical fiber element fitting hole 24 provided in the same to extend eccentric to the center axis of the circular cylindrical body and in parallel with the first optical fiber element fitting hole 23, and an eccentric cylindrical hole 25 provided in the rear region of the circular cylindrical body to extend with the center axis coinciding with the center line between the first and second optical fiber element fitting holes 23 and 24, into which an optical fiber core is fitted, wherein the cylindrical sleeve 22 is monolithically formed by injection molding of a metal material.