The Diocese of Coutances (–Avranches) is a Latin diocese of the 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 (–Avranches).

Coutances Cathedral is a Gothic Catholic cathedral constructed from 1210 to 1274 in the town of Coutances, Normandy, France. It incorporated the remains of an earlier Norman cathedral.