It is intended to provide a compound that is effective as a diagnostic imaging probe that targets amyloid, and a diagnostic agent for Alzheimers disease comprising the compound. Provided are a compound represented by the following formula (1), or a salt thereof: wherein R 1 is a radioactive halogen substituent, 0 to 2 of A 1 , A 2 , A 3 and A 4 represent N, and the rest represent CH, and a diagnostic agent for Alzheimers disease which comprises a compound represented by the above formula (1) or a salt thereof. The present compound and the present diagnostic agent for Alzheimers disease transfer into brain after administration, and indicate good accumulation on amyloid deposited in the brain.
