The Finnish national road 51 (Finnish: Kantatie 51; Swedish: Stamväg 51) is the 2nd class main route between the major cities of Helsinki and Raseborg in southern Finland.

[1] It runs from Ruoholahti in Helsinki and passes through Espoo to Kirkkonummi as a motorway[2] called Länsiväylä (Swedish: Västerleden), where it continues to Karis in Raseborg as a smaller road.

The road passes through the following localities: