The present invention offers a method of manufacture of sustained-release formulation composition which includes a step of spray drying a composition that contains (1) an active ingredient, (2) a resin ingredient, and (3) a solvent, using a spray dryer and controlling the exit temperature of the spray dryer, wherein solvent content in the composition after spray drying is 5 mass % or less, and the composition after the aforementioned spray drying does not substantially contain decomposed matter of the aforementioned active ingredient.
