The Diocese of Tagum (Latin: Dioecesis Tagamna) is a diocese of the Catholic Church in the Philippines. The diocese is a suffragan of the Archdiocese of Davao. It was canonically erected as Prelature Nullius on 13 January 1962 by Pope John XXIII, with Joseph Regan M.M. as its local ordinary. It was elevated to the status of a diocese on 11 October 1980 by Pope John Paul II, who appointed Pedro Dean as its first Filipino bishop ordinary, and Ramon Villena as the auxiliary bishop.