Amour de poche (1957)
Amour de poche is a French comedy Fantasy film from 1957, directed by Pierre Kast, written by France Roche, starring Jean Marais. The scenario was based on a novel "Diminishing Draft" of Waldemar Kamempfert. The film was known under the title "Girl in His Pocket" (USA), "Alchimie der Liebe" (West Germany), "Nude in His Pocket".
More at Wikipedia.