A periphery vehicle determination apparatus disposed in a host vehicle includes a behavior obtaining section obtaining a behavior related information of an immediately adjacent object, a vehicle-to-vehicle communication device, an information obtaining section obtaining vehicle information sets from periphery vehicles, a specifying section specifying a vehicle information set from an immediately adjacent vehicle based on the behavior related information, a transceiving section transmits and receives an immediately adjacent information, and an anteroposterior relation determination section specifying an anteroposterior relation of the periphery vehicles in a one-dimensional direction by correlating the immediately adjacent informations transmitted from the periphery vehicles based on a repeated identification information included in at least two of the immediately adjacent informations.