A compound effective as a probe targeting amyloid for image diagnosis and a reagent comprising the compound for detecting amyloid deposited on a biological tissue are provided. Provided are a compound represented by the following formula (1): wherein R1, R2 and R3 independently represent a group selected from the group consisting of a hydrogen, hydroxyl group, alkyl substituent with 1 to 4 carbon atoms, alkoxy substituent having alkyl chain with 1 to 4 carbon atoms and halogen substituent, excluding the case where two or more of the substituents R1, R2 and R3 are hydrogen, R4 is a group selected from the group consisting of a hydrogen, hydroxyl group, alkoxy substituent having alkyl chain with 1 to 4 carbon atoms and halogen substituent, and m is an integer of 1 to 4, provided that at least one of R1, R2, R3 and R4 represents a radioactive halogen substituent, and a reagent comprising the same.