PROBLEM TO BE SOLVED: To provide a biologically active granulated substance having good granulating properties and being release-controlled over a long period of time by suppressing the release rate of a biologically active substance when sprayed in a seedling box, a paddy field and a farmland.SOLUTION: A production method of a biologically active granulated substance is characterized in that a mixture containing (A) a biologically active substance, (B) an organic polyisocyanate and (C) an isocyanate reactive compound as essential components is granulated with an extrusion granulator and the granulated substance is heat-treated at a temperature of 40 to 120°C.