The invention relates to a mixing device (D, D') for mixing a powdered product and a liquid product, particularly for food preparation for babies, said device comprising a main container (1) closed on a first end (16) by a detachable cover (2), and a secondary container (6) forming a reservoir for receiving a dose of powdered product, said secondary container (6) being detachably mounted on a second end (12) of the main container (1). The mixing device is characterised in that the main container (1) comprises a spring in the form of a top (5, 5', 5"), said spring in the form of a top (5, 5', 5") being detachable from the main container (1) and free to move in said main container (1) when said main container (1) is manually shaken by a user.
