A sliding nozzle for a molten steel receiving vessel, which comprises: an upper nozzle (22) made of a refractory inserted vertically into a bottom wall of a molten steel receiving vessel; a fixed plate (23) made of a refractory secured horizontally and stationarily to a lower end of the upper nozzle; a horizontally and reciprocally movable sliding plate (24) made of a refractory arranged below the fixed plate; a lower nozzle (25) made of a refractory secured vertically and stationarily below the sliding plate, the lower nozzle comprising a nozzle body (27) and a metallic frame (28) fitted to a flange (27A) at an upper end of the nozzle body, the lower nozzle having a length sufficient to cause a lower end portion thereof to be immersed into molten steel in a mold; a fitting device (30) for pressing the lower nozzle (25) against the lower end of the upper nozzle (22) through the sliding nozzle (24) and the fixed plate (23); and a driving unit (26) for causing the sliding plate ( 24) to slide horizontally and reciprocally between the fixed plate (23) and the lower nozzle (25).