The present invention provides a method for producing a granular agent for agricultural and horticultural use, in which a powdery agrochemical composition is formed to granules using a horizontal extrusion type granulator, wherein the granulator comprises a hopper for supplying a kneaded mixture of the powdery agrochemical composition and water, a screw for kneading and extruding the kneaded mixture, a screw case for storing the screw, a screen for forming the kneaded mixture to a strand shape, which is provided on a screw case wall that is distant from the hopper and parallel to the screw axis, and a cooling member for cooling a screw case wall that is distant from the hopper and provided on a side of a bearing of the screw, and the powdery agrochemical composition contains in total 20 to 80% by weight of component having a solubility of 4,000 to 500,000 ppm at 20℃ at pH 3 to 9.本發明提供一種農園藝用顆粒劑之製造方法，其係使用橫向擠出造粒機將粉末狀農藥組成物成形為顆粒者，其特徵在於：上述橫向擠出造粒機具有：給料斗，其係用以供給上述粉末狀農藥組成物與水之混練物；螺桿，其係用以捏合上述混練物並將其擠出；螺桿箱，其收納上述螺桿；篩，其係為了將上述經捏合之混練物成形為股(strand)狀而設置於遠離上述給料斗之側之與螺桿軸平行的螺桿箱壁；及冷卻手段，其係用以冷卻遠離上述給料斗之側的螺桿之軸承側之螺桿箱壁；且上述粉末狀農藥組成物含有於水溫20℃、pH值3~9時之水溶解度為4,000~500,000ppm的成分合計20~80重量%。
