[Problem] To produce: a compound which is effective as a diagnostic imaging probe that targets amyloid and a diagnostic agent for Alzheimers diseases and which comprises the compound. [Solution] A compound represented by formula (1) (wherein R1 represents a radioactive halogen substituent and A1 and A2 independently represent CH or N) or a salt thereof and a diagnostic agent for Alzheimers disease and which comprises a compound represented by the above-mentioned formula or a salt thereof. The compound and the diagnostic agent for Alzheimers disease can migrate into the brain after being administered and can be accumulated satisfactorily onto amyloid that has been deposited ON the brain.
