The duties of Benkan were mainly supervising the officials of the ministries and the organizations under the ministries, as well as administering the ruling of reception of general notification, examination and decision of the matters inside the government, signatures to drafts, judgment on delay or negligence in public services, night-watch duties of the government offices and morning ceremony Choshu of Kokushi (Taihorei Shokuinrei).
その職掌は各省とその傘下の役職の監督が主であり、庶事の受け付け、官内の糺断と決裁、起案文への署名、公務の遅滞や過失の判断、諸官庁の宿直と諸国司の朝集の裁定をつかさどった（大宝令職員令）。