It is intended to provide a compound that iseffective as a diagnostic imaging probe that targetsamyloid, and a diagnostic agent for Alzheimers diseasecomprising the compound. Provided are a compoundrepresented by the following formula (1), or a saltthereof:(see formula 1)wherein R1 is a radioactive halogen substituent, 0 to 2of A1, A2, A3 and A4 represent N, and the rest representCH, and a diagnostic agent for Alzheimers disease whichcomprises a compound represented by the above formula (1)or a salt thereof. The present compound and the presentdiagnostic agent for Alzheimers disease transfer intobrain after administration, and indicate goodaccumulation on amyloid deposited in the brain.
