The men's marathon was part of the Athletics at the 1964 Summer Olympics program in Tokyo.

[1] The maximum number of athletes per nation had been set at 3 since the 1930 Olympic Congress.

Returning runners from the 1960 marathon included defending champion Abebe Bikila of Ethiopia and ninth-place finisher Osvaldo Suárez of Argentina.

[2] Luxembourg (not counting Michel Theato, the gold medalist in 1900 who was Luxembourg-born but registered as a French competitor) Nepal, Puerto Rico, Rhodesia, Northern Rhodesia, Tanzania, Thailand, and Vietnam each made their first appearance in Olympic marathons.

The United States made its 15th appearance, the only nation to have competed in each Olympic marathon to that point.