An inner-ring restraint device restricting an inner ring of a hub bearing of a vehicle at the time of manufacturing said hub bearing including a shaft body, said inner ring provided on an outer periphery of said shaft body and an outer ring provided on an outer periphery of the inner ring so as to rotate freely by a plurality of rolling elements, said inner-ring restraint device comprising: a restraint ring formed of a plurality of pieces (20a, 20b, 20c, 20d, 20e and 20f) arranged to form a ring shape, and adapted to be placed coaxially with the shaft body and to restrict an outer peripheral portion of the inner ring by reducing in diameter; a support plate (30, 30a) having a ring shape, that supports said plural pieces (20a, 20b, 20c, 20d, 20e and 20f), said support plate (30, 30a) being adapted to be placed coaxially with the shaft body, and to move along an axial direction of the shaft body so as to respectively move in a state where the plural pieces (20a, 20b, 20c, 20d, 20e and 20f) arranged in said restraint ring shape form a restraint ring of a reduced or expanded diameter; and a ring-shaped operation plate (40, 40a) arranged on an outer periphery of the restraint ring, and connected to the support plate so as to allow relative movement in the axial direction between the ring-shaped operation plate and the support plate, such that when the ring-shaped operation plate comes relatively closer to the support plate, a pressure is applied on the respective plural pieces (20a, 20b, 20c, 20d, 20e and 20f) in a direction of reducing the diameter of the restraint ring, characterised in that said support plate (30, 30a) supports said plural pieces (20a, 20b, 20c, 20d, 20e and 20f) from a hub bearing side, said support plate (30, 30a) being in use positioned in the axial direction closer to the hub bearing than the restraint ring. a restraint ring formed of a plurality of pieces (20a, 20b, 20c, 20d, 20e and 20f) arranged to form a ring shape, and adapted to be placed coaxially with the shaft body and to restrict an outer peripheral portion of the inner ring by reducing in diameter; a support plate (30, 30a) having a ring shape, that supports said plural pieces (20a, 20b, 20c, 20d, 20e and 20f), said support plate (30, 30a) being adapted to be placed coaxially with the shaft body, and to move along an axial direction of the shaft body so as to respectively move in a state where the plural pieces (20a, 20b, 20c, 20d, 20e and 20f) arranged in said restraint ring shape form a restraint ring of a reduced or expanded diameter; and a ring-shaped operation plate (40, 40a) arranged on an outer periphery of the restraint ring, and connected to the support plate so as to allow relative movement in the axial direction between the ring-shaped operation plate and the support plate, such that when the ring-shaped operation plate comes relatively closer to the support plate, a pressure is applied on the respective plural pieces (20a, 20b, 20c, 20d, 20e and 20f) in a direction of reducing the diameter of the restraint ring, characterised in that said support plate (30, 30a) supports said plural pieces (20a, 20b, 20c, 20d, 20e and 20f) from a hub bearing side, said support plate (30, 30a) being in use positioned in the axial direction closer to the hub bearing than the restraint ring.