Provided is a method for manufacturing an agricultural and horticultural granule formulation, said method comprising molding a powdery pesticide composition into granules using a horizontal extrusion type granulator, characterized in that: the horizontal extrusion type granulator is equipped with a hopper for supplying a mixture of the powdery pesticide composition with water, a screw for kneading and extruding the mixture, a screw case for housing the screw, a screen for molding the kneaded mixture into strands, said screen being provided on a screw case wall on the side remote from the hopper that is in parallel to the screw axis, and a cooling means for cooling a screw case wall on the side of a screw bearing on the side remote from the hopper； and the powdery pesticide composition contains 20-80 wt% in total of component(s) having a solubility in water at a water temperature of 20oC at pH 3-9 of 4,000-500,000 ppm.
