Therefore, the Nakatsukasa-Kyo (corresponding to Shoshiinojo [Senior Fourth Rank Upper Grade]), the Secretary of Nakatsukasa-sho, was conventionally chosen from the Imperial Princes with a rank equivalent to or higher than Shihon (the fourth rank of Imperial Princes' rank) exclusively in and after the Heian period.
そのためこの官庁の長官である中務卿（正四位上相当）は平安時代以降はもっぱら四品以上の親王から任命されることとなっていた。