phthalonitrile derivatives represented by the formula : ## str1 ## n -- c m h 2m + 1 , ## str3 ## or a halogen atom , wherein m represents an integer of 1 to 9 and n represents 0 , 1 or 2 ), but at least one of x and y does not represent a methyl group , and y does not not represent an alkyl group having 1 to 9 carbon atoms or an alkoxy group having 1 to 9 carbon atoms in the case that x represents r 1 h and r 1 represents an alkyl group having 1 to 9 carbon atoms ).