[Object] A paddy seed treatment agent containing a herbicidal active component and having a sufficient herbicidal effect, while having a reduced risk of herbicide injury to paddy rice, a method for treating paddy seeds using the paddy seed treatment agent, paddy seeds, and a method for controlling paddy field weeds by sowing and cultivating the paddy seeds, are provided.[Solution] The paddy seed treatment agent contains fenquinotrione or a salt thereof as a herbicidal active component. The method for controlling paddy field weeds includes sowing and cultivating paddy seeds treated with this paddy seed treatment agent, and the like.本發明係提供一種儘管已含有除草活性成分，亦能減低對於水稻之藥害發生的危險性，且亦一併具有充分之除草效果的水稻種子處理劑及使用該水稻種子處理劑之水稻種子之處理方法及水稻種子以及藉由播種該水稻種子進行栽培之水田雜草之防除方法。作為除草活性成分，係含有芬昆特(Fenquinotrione)或其鹽之水稻種子處理劑。又，播種以此水稻種子處理劑處理之水稻種子進行栽培之水田雜草之防除方法等。
