A compound represented by the following general formula (IA) or (IB) (R1 represents an electron withdrawing substituent, R2 and R3 represent a hydrogen atom or a halogen atom R4 and R3 represent a hydrogen atom, an alkylcarbonyl group, or an alkylcarbonyloxymethyl group, and R6 represents a hydrogen atom or an alkyl group) or a salt thereof, and a reagent for measuring hydrogen peroxide comprising the compound or a salt thereof.
