To provide a solid/liquid separator enhancing draining efficiency of water contained in residue when separating sewage containing residue into solid and liquid, and eliminating clogging by the residue occurring during separation.

The separator is provided with a charge port 3 charging sewage containing residue, a separation device 10 separating the charged sewage into residue and liquid while horizontally and circularly moving it, and a discharge port 4 discharging the residue separated from liquid in the separation device 10 to the outside. The separation device 10 is provided with first multiple corrugated plates 30 fixed within a body 2 of the device 10, second corrugated plates 40 disposed between the first plates 30 and circularly moved by the rotation of drive shafts 11, 12, and a drive motor 13 rotating the shafts 11, 12.