Abstract: A lost sand collecting apparatus, according to the present invention, comprises: a filling frame which has a plurality of plates, extends in the lateral direction and forms a plurality of filling spaces; and a collecting means which is provided on the filling frame and is positioned so as to correspond to the filling spaces. The plurality of plates are overlapped so as to be parallel to each other and the plates adjacent with a fixed distance therebetween are partly connected to one another. The collecting means can be formed in a flat structure protruding upward from the filling frame and disposed on the back of the filling spaces with respect to the littoral current toward the sea, and comprises a barrier layer or a web layer. The barrier layer or the web layer is curved toward the littoral current toward the sea.