The present invention is directed to provide an apparatus which is capable of continuously and effectively shattering wastes including organic substances and even such wastes as including fat or other doggy substances suspended in a water, without obstructing an operation of the apparatus. The apparatus comprises a cylindrical vertical housing having annular passages partitioned by adjacent two or more substantially concentric cylindrical walls, a water injection device which produces a pressurized water flow so as to supply high-speed water flows tangentially into the annular passages, and a nozzle which is disposed in any one of the cylindrical walls so as to supply a slurry including organic substance particulates into the high-speed water flows and thus ultrafinely shatters the organic granular substances into particulates having the size of a few micrometers by cavitation effect and/or shearing effect produced in the high-speed water flows. As the nozzle may be used a vertical slot formed by piercing the cylindrical wall.