It is intended to provide a compound that is effective as a diagnostic imaging probe that targets amyloid, and a diagnostic agent for Alzheimer's disease comprising the compound. Provided are a compound represented by the following formula (1), or salt thereof: wherein R 1 is a radioactive halogen substituent, A 1 and A 2 independently represent CH or N, and a diagnostic agent for Alzheimer's disease, comprising the compound represented by the above formula or a salt thereof. The above compound and the above diagnostic agent for Alzheimer's disease transfer into brain after administration, and indicate good accumulation on amyloid deposited in the brain.