Apparatus for treating skin comprising: - a body comprising a casing (21, 22) forming a grippable region, - electrical means for supplying power, arranged in said body, - at least one treatment head (3, 6, 7, 8, 9), - at least one light source, - at least one light guide having a projection area that is intended to receive the light emitted by said at least one light source and to project at least one light beam intended for a region of skin, said at least one light guide comprises a face opposite said projection area, said opposite face comprising distributing means intended to distribute the light over said projection area, the light guide being made of a one-piece part having both the projection area and the opposite face which is facing it, and said distribution means comprising at least one area (S1, S2) at least partially reflective intended to reflect some of the light towards said projection area, said at least one light guide having at least one transversal cross-section for passing the light which is a cross-section passing through a plane perpendicular to said projection area, said transversal cross-section being secant with the projection area and said at least one area respectively following a first straight line and a second straight line, said at least one light source being arranged at an end of said transversal cross-section between the first straight line and the second straight line, characterised in that said at least one light guide is a revolving solid of said transversal cross-section about a central axis (Δ) and in that said at least one light source comprises a plurality of light-emitting diodes distributed regularly about said light guide. - a body comprising a casing (21, 22) forming a grippable region, - electrical means for supplying power, arranged in said body, - at least one treatment head (3, 6, 7, 8, 9), - at least one light source, - at least one light guide having a projection area that is intended to receive the light emitted by said at least one light source and to project at least one light beam intended for a region of skin, said at least one light guide comprises a face opposite said projection area, said opposite face comprising distributing means intended to distribute the light over said projection area, the light guide being made of a one-piece part having both the projection area and the opposite face which is facing it, and said distribution means comprising at least one area (S1, S2) at least partially reflective intended to reflect some of the light towards said projection area, said at least one light guide having at least one transversal cross-section for passing the light which is a cross-section passing through a plane perpendicular to said projection area, said transversal cross-section being secant with the projection area and said at least one area respectively following a first straight line and a second straight line, said at least one light source being arranged at an end of said transversal cross-section between the first straight line and the second straight line, characterised in that said at least one light guide is a revolving solid of said transversal cross-section about a central axis (Δ) and in that said at least one light source comprises a plurality of light-emitting diodes distributed regularly about said light guide.