An optical connector, comprising: an optical-fiber core-wire holding member having a fiber core-wire insertion hole, into which an optical fiber core wire of an optical fiber is inserted, with a front end face of the optical fiber core wire inserted into the fiber core-wire insertion hole so as to be exposed; and a lens member having a lens unit arranged on an axis of the optical fiber core wire and made of a light transmitting material, wherein an adhesive having a refractive index N, which is between a refractive index N1 of the lens member and a refractive index N2 of the optical fiber core wire, and having optical transparency is filled between the front end face of the optical fiber core wire and an end face of the lens member opposite to the front end face of the optical fiber core wire, wherein the optical-fiber core-wire holding member includes a cylindrical portion having a small outer diameter and a cylindrical portion having a large outer diameter, the large-diameter cylindrical portion being integrally formed with the small-diameter cylindrical portion, the fiber core-wire insertion hole is formed at the center of the small-diameter cylindrical portion and the large-diameter cylindrical portion, the fiber core-wire insertion hole is formed of a small-diameter hole formed in the small-diameter cylindrical portion and a large-diameter hole formed in the large-diameter cylindrical portion, the exposed optical fiber core wire is inserted into the small-diameter hole, wherein the adhesive is also filled between an inner periphery of the small-diameter hole and an outer periphery of the exposed optical fiber core wire, the optical fiber core wire coated with an internal coating portion is inserted into the large-diameter hole, wherein an inner periphery of the large-diameter hole and an outer periphery of the internal coating portion are fixed by a laser welding portion, and the adhesive is also filled between an outer periphery of the small-diameter cylindrical portion of the optical-fiber core-wire holding member and an inner surface of an inner-ferrule insertion hole of the lens member. an optical-fiber core-wire holding member having a fiber core-wire insertion hole, into which an optical fiber core wire of an optical fiber is inserted, with a front end face of the optical fiber core wire inserted into the fiber core-wire insertion hole so as to be exposed; and a lens member having a lens unit arranged on an axis of the optical fiber core wire and made of a light transmitting material, wherein an adhesive having a refractive index N, which is between a refractive index N1 of the lens member and a refractive index N2 of the optical fiber core wire, and having optical transparency is filled between the front end face of the optical fiber core wire and an end face of the lens member opposite to the front end face of the optical fiber core wire, wherein the optical-fiber core-wire holding member includes a cylindrical portion having a small outer diameter and a cylindrical portion having a large outer diameter, the large-diameter cylindrical portion being integrally formed with the small-diameter cylindrical portion, the fiber core-wire insertion hole is formed at the center of the small-diameter cylindrical portion and the large-diameter cylindrical portion, the fiber core-wire insertion hole is formed of a small-diameter hole formed in the small-diameter cylindrical portion and a large-diameter hole formed in the large-diameter cylindrical portion, the exposed optical fiber core wire is inserted into the small-diameter hole, wherein the adhesive is also filled between an inner periphery of the small-diameter hole and an outer periphery of the exposed optical fiber core wire, the optical fiber core wire coated with an internal coating portion is inserted into the large-diameter hole, wherein an inner periphery of the large-diameter hole and an outer periphery of the internal coating portion are fixed by a laser welding portion, and the adhesive is also filled between an outer periphery of the small-diameter cylindrical portion of the optical-fiber core-wire holding member and an inner surface of an inner-ferrule insertion hole of the lens member.