This is a very cool poster. It is an original release poster from France, size is 60x80 cm (23x31 in), a size known as "Petite Affichette".
The artist for this poster was a gentleman named Boris Grinsson (1907-1999), who provided the artwork for LOTS of French film posters, over 2000 I believe. There is a book available on his poster art from French Amazon, some of the most striking French posters ever made were done by M. Grinsson.
Boris Grinsson on Amazon