Abstract: A compound represented by the formula: [wherein R1 represents a hydrogen atom, a halogen, atom, alkyl group, etc., R2 represents a hydrogen atom, a halogen atom, alkyl group, etc., R3, R4, R5, R6 and R7 each independently represent a hydrogen atom, a halogen atom, a substitutable alkyl group, a substitutable alkenyl group, alkynyl group, a substituteable cycloalkyl group, etc., or R3, R4, R5, R6 and R7 may form a ring which may be substituted, which is formed by the adjacent two of them with carbon atoms to which the respective substituents are bonded, m and n each independently represent 0 or 1.] a salt thereof, an ester derivative thereof and an agricultural chemical containing the same as an effective ingredient, and a herbicidal composition containing the compound and a second herbicidally active compound as effective ingredients.