<；P>；PROBLEM TO BE SOLVED: To obtain a coating film for producing a coated granular plant active substance that has a short elution control period, sufficiently controls an initial elution amount, has biodegradability and is produced without a solvent. <；P>；SOLUTION: The polyurethane coating film having the properties is obtained by using an adduct of an alkylene oxide to a polycaprolactone having a high hydroxyl equivalent and low viscosity as a polyol. The alkylene oxide is preferably propylene oxide and/or ethylene oxide and the number of addition of the alkylene oxide added per functional group of the polycaprolactone is preferably &le；7. <；P>；COPYRIGHT: (C)2008,JPO&INPIT
