Pyrazolinone derivatives represented by general formula (I), wherein R<;1>;, R<;2>;, R<;3>;, R<;4>; and R<;5>; are the same or different and each represents hydrogen, halogeno, alkyl, haloalkyl, alkoxy, etc.; R<;6>; represents optionally substituted alkyl, etc.; X represents optionally substituted alkyl, etc.; and Y represents oxygen or sulfur. <;CHEM>;