The present invention relates to an aerosol device including: —a container containing: —one or more propellants, and —a composition including one or more fixing polymers and/or one or more styling powders including one or more water-insoluble inorganic compounds, the propellant or propellants possibly being present in the composition or in the container, separate from the composition, —an aerosol device for distributing the aerosol composition, including a diffuser having at least three spraying apertures for spraying the composition in a main spraying direction. The invention further provides a method for shaping the hair and/or maintaining the style, including a step of applying to the wet or dry hair a cosmetic composition sprayed from a specific aerosol device.