The Roman Catholic Diocese of Coutances (Lat:Constantiensis) is a diocese of the Latin Rite of the Roman Catholic church in France. Its mother church is the Cathedral of Coutance in the commune of Coutances in France. The diocese is suffragan of the Archbishop of Rouen and comprises the entire department of Manche. It was enlarged in 1802 by the addition of the former Diocese of Avranches and of two archdeaconries from the Diocese of Bayeux. Since 1854 its bishops have held the title of Bishop of Coutances and Avranches.