To provide a sand separating and washing apparatus capable of efficiently removing floating refuse in a tank at an overflowing part.

In the sand separating and washing apparatus equipped with a solid-liquid separation tank 1 into which polluted sand mixed water is introduced and the sedimentation tank 2 installed under the solid-liquid separation tank 1. The solid-liquid separation tank 1 is equipped with a cylindrical wall 3 which produces a revolving flow falling along its peripheral wall by allowing polluted sand mixed water to flow in a tangential direction from an inflow pipe 7, the bottom wall 4, which comprises an inverted truncated cone shape, arranged to the bottom part of the cylindrical wall 3 and the drain duct 5 for discharging outward the water in the vicinity of the center of the bottom wall 4, the separation hopper 6 with an inverted truncated cone-shaped installed in the cylindrical wall 3 above the inflow pipe 7 and into which the returning revolving flow flows and the cylindrical overflowing weir 8 installed at the center of the upper part of the cylindrical wall 3 to allow the water, which flows in the separation hopper 6 to overflow.