To provide an optical cable unit capable of being easily discriminated without reading marking and characters written on the surface of a cable outer sheath and without leaving bent tendency on a cable when performing discrimination by leakage light due to bending of the optical cable unit, and to provide an optical cable assembly comprising the cable units, and a method of detecting a prescribed optical cable unit.

An optical cable unit 11 collectively coated with the cable outer sheath 14 by being arranged so as to juxtapose tensile strength wires 13 in one row on both side of an optical fiber core 12 for communication stores the optical fiber core 17 for discrimination at a position separated from the coated optical fiber core 12 for communication in the cable outer sheath 14. Moreover, a display body for indicating the position of the optical fiber core 17 for discrimination is formed along a longitudinal direction of the cable outer sheath 14 with a projected, recessed or colored band.