Abstract: The subject of this research is the role of the cult of imperial house in ideology of the Roman Emperor Trajan (98-1170). The article reveals correlation between the image of Trajan’s family and the formation of the image of the emperor himself within the official ideology. The author examines the peculiarities of the cult of imperial house pertaining to such relatives of Trajan, as his adoptive father Nerva, biological father Trajan Senior, wife Plotina, sister Maricia, and niece Matidia. The author highlights two stages of development of the imperial house cult at the time of Trajan. The scientific novelty consists in the fact that this article is first in the Russian historiography to thoroughly explore the role of the imperial house cult in Trajan’s ideology. The immediate circle of the emperor had to correspond the image of the emperor himself. At the beginning of Trajan’s reign (98-105) we can observe moderation in favors, modesty, honor of his adoptive father Nerva, and respect for other family members. At the second stage (105-112), we can observe a significant amplification of the imperial house cult, which expressed in deification of Trajan’s the dead relatives and glorification of those alive. The author also notes the uniqueness of the situation, in which the Emperor Trajan simultaneously had two deified fathers, as well as reveals the essence of the conflict between honoring the biological father and the adoptive father.