To provide a washing apparatus capable of sufficiently washing stain sticking on a used sheet made of a synthetic resin.

The washing apparatus for the sheet made of the synthetic resin includes a crusher 33 for crushing agricultural polyethylene sheets into crushed pieces, dry washing machines 56 and 57 which release the stain stuck on the surface of the crushed pieces coming out from the crusher 33 by an impact or a frictional force given by a high speed rotating body 49, and a soil and sand separating machine 60 which has a screen rotating cylinder and discharges the soil and the sand and dust separated from the crushed pieces by passing the crushed pieces coming out from the dry washing machines 56 and 57 through the screen rotating cylinder with a carrying air through the screen of the screen rotating cylinder.