Le Mans Cathedral (Cathédrale St-Julien du Mans) is a Roman Catholic cathedral situated in Le Mans, France. It is dedicated to Saint Julian of Le Mans, the city's first bishop.

It is the seat of the Bishop of Le Mans.

The cathedral is architecturally distinguished by the striking contrast between the Romanesque nave and the High Gothic choir (begun in 1217 and completed around 1254). The building as a whole was intended at one point to be even larger, but building was stopped for lack of money. There have been many restorations over the centuries, but now natural aging and air pollution mean that the cathedral is almost constantly being renovated.

Every Sunday morning, there is a traditional market in the Place des Huguenots beneath the eastern end of the cathedral.