Prosthetics (1) of the intervertebral disc, comprising two pieces (5, 6) that extend mainly on a piano and a flexible element (7) interposed between these two pieces (5, 6)； This flexible element (7) is a spherical ball and comprises, on two opposite sides, two areas of contact with these pieces (5, 6) and allows, through its elastic deformation, approximation / distancing movements of said pieces (5 , 6) according to a direction perpendicular to said piano； each piece (5, 6) has a rounded surface adapted to come into contact with the corresponding contact area of the flexible element (7)； the pieces (5, 6) having guiding means (23, 33) of their approach / distancing movements from each other, only these guiding means (23, 33) allowing these approximation / distancing movements of the pieces (5, 6)； characterized in that: - said rounded surfaces are formed by cups (25, 35) in hollow spherical caps arranged substantially in the center of said parts (5, 6), which receive this flexible element (7)； and - said parts (5, 6) form a free space (28) that surrounds the entire periphery of the flexible element (7), outside said contact areas.PrOtesis (1) de disco intervertebral, que comprende dos piezas (5, 6) que se extienden principalmente en un piano y un elemento flexible (7) interpuesto entre estas dos piezas (5, 6)； este elemento flexible (7) es una bola esferica y comprende, en dos lados opuestos, dos zonas de contacto con estas piezas (5, 6) y permite, a traves de su deformacion elastica, movimientos de aproximacion/distanciamiento de dichas piezas (5, 6) de acuerdo con una direccion perpendicular a dicho piano； cada pieza (5, 6) tiene una superficie de forma redondeada adaptada para entrar en contacto con la zona de contacto correspondiente del elemento flexible (7)； teniendo las piezas (5, 6) unos medios de guiado (23, 33) de sus movimientos de aproximacion/distanciamiento entre sí, permitiendo unicamente estos medios de guiado (23, 33) estos movimientos de aproxima
