The Compagnie du chemin de fer de Caen à la mer (CM) was an early French railway company.
The first railway to reach Caen, on 18 November 1855, was the Chemins de fer de l'Ouest's line from Paris (Gare Saint-Lazare) and Mantes-la-Jolie to Cherbourg. In the early part of the 19th century only the country's main cities and towns were favoured by a rail service, but by the 1850s the local authorities in Calvados were demanding that the département be served by additional local railways for the benefit of industry.
The CM's line in Calvados was inaugurated on 30 June 1875 and originally ran for 16 km between stations at Caen Saint-Martin and Luc-sur-Mer.
In July 1876, the line was extended by 8 km from Luc-sur-Mer to Courseulles.
A 4-km-long connection between the CM and the Ouest company's main line in Caen was opened on 12 September 1877 and several intermediate stations – at La Folie, Malon, Le Cizey, and Épron – were opened to passengers.
All the company's tracks were 1,435 mm (4 ft 8 1⁄2 in) standard gauge; however in 1900 a third rail was laid between Luc-sur-Mer and Courseulles to allow through running to the latter town of 600-mm-gauge Chemins de fer du Calvados (CFC) trains operating from Caen via the CFC's Ouistreham to Luc-sur-Mer branch.
The company makes a profit during the summer season, but most services stop during World War I, with only 3 return trips operating. After the Armistice, normal operation resumed and the company diversified its operations with a bus service to provide a corresponding bus to its trains.