A compound that is effective as a diagnostic imaging probe that targets amyloid including is represented by the following formula (1), or salt thereof: wherein R1 is a radioactive halogen substituent, A1 and A2 independently represent CH or N. A diagnostic agent for Alzheimer's disease includes 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.