Career
Born in Saint-Alexis-de-la-Grande-Baie, Quebec, he was a merchant by career. Gagnon was educated at the Chicoutimi Seminary. He was first elected to Parliament at the Chicoutimi riding in the 1945 general election then re-elected for successive terms in 1949 and 1953.
Gagnon was defeated by Rosaire Gauthier of the Liberal party.