To instantaneously change the grain diameter distribution of finished product crushed sand to a desired pattern by sorting out a product on the lowest sieve in arbitrarily selected proportions, and transferring one of the sorted products to the sieve to a return line, while transferring the other product to a finished product line.

A raw material received by a raw material bin 1 is dispensed by vibration feeder 2, supplied to a rotary crusher 3 and crushed, and further, the crushed product is charged into a vibrating sieve 4 with sieves and sorted out with the sieves. The vibrating sieve 4 consists of a sieve with a large mesh at the upper stage and a sieve with a small mesh at the lower stage. The product on the sieve of the upper stage sieve is all supplied to a return line 5, while the product on the sieve of the lower stage, after moving the bottom stage sieve is moved to a product passage 10 integrally connected to the vibrating sieve 4. In the product passage 10, the product is sorted out in arbitrarily selected proportions. Thus it is possible to easily and conveniently obtain sand including oversized grains in arbitrarily selected proportions.