An eyeglass frame coupling structure having a separable connection portion formed on a given position of an eyeglass frame, which fixes the outer edge of a lens thereto, so that if the connection portion is separated, the lens is separated from the eyeglass frame, and if the connection portion is connected, the lens is fitted to the eyeglass frame, wherein the separable connection portion is separable into a lower part and an upper part, each having a rear surface as well as an end surface that is directed towards the end surface of the other part, the eyeglass frame coupling structure comprising: a receiving portion formed in one of said two parts of the separable connection portion and a protruding portion formed on the other of said two parts and adapted to abut the receiving portion, wherein the receiving portion has a receiving cavity (a) which opens on the end surface of the respective part and the protruding portion has a protrusion (d) adapted to be received in the receiving cavity (a) and a screw hole (f) formed in the forward/backward direction in the protrusion (d), characterised in that: the receiving cavity (a) opens continuously on the end surface and rear surface of the respective part of the separable connection portion, and has a bottom wall facing the opening of the receiving cavity (a) on said rear surface, an engaging groove (c) is formed incised to a given depth on a portion or the whole portion of each side wall of the receiving cavity (a), starting from the end surface of the respective part of the separable connection portion, a fixing recess (b) is formed on said bottom wall of the receiving cavity (a), the protrusion (d) is in the extension of the rear surface of the protruding portion, and thus forms part of the rear surface of the respective part of the separable connection portion, an engaging step (e) is formed protruding outwardly from the outermost peripherial portion of the protrusion (d) in such a manner as to be insertable into the engaging groove (c), and the eyeglass frame coupling structure further comprises a fixing screw adapted to be screw-fastened to the screw hole (f), whereby, when the separable connection portion is connected, the engaging step (e) is inserted into the engaging groove (c), the protrusion (d) extends in the opening of the receiving cavity (a) on the rear surface of the respective part of the separable connection portion and the screw hole (f) communicates with the fixing recess (b), the fixing screw being adapted so that an end of the fixing screw is just inserted into the fixing groove (b), thus preventing the separable connection portion of the eyeglass frame from protruding outwardly from the eyeglass frame. the receiving cavity (a) opens continuously on the end surface and rear surface of the respective part of the separable connection portion, and has a bottom wall facing the opening of the receiving cavity (a) on said rear surface, an engaging groove (c) is formed incised to a given depth on a portion or the whole portion of each side wall of the receiving cavity (a), starting from the end surface of the respective part of the separable connection portion, a fixing recess (b) is formed on said bottom wall of the receiving cavity (a), the protrusion (d) is in the extension of the rear surface of the protruding portion, and thus forms part of the rear surface of the respective part of the separable connection portion, an engaging step (e) is formed protruding outwardly from the outermost peripherial portion of the protrusion (d) in such a manner as to be insertable into the engaging groove (c), and the eyeglass frame coupling structure further comprises a fixing screw adapted to be screw-fastened to the screw hole (f), whereby, when the separable connection portion is connected, the engaging step (e) is inserted into the engaging groove (c), the protrusion (d) extends in the opening of the receiving cavity (a) on the rear surface of the respective part of the separable connection portion and the screw hole (f) communicates with the fixing recess (b), the fixing screw being adapted so that an end of the fixing screw is just inserted into the fixing groove (b), thus preventing the separable connection portion of the eyeglass frame from protruding outwardly from the eyeglass frame.