A deicing device for propfan-type aircraft propulsion unit blades, wherein the propulsion unit includes a turbomachine that drives in rotation at least one rotor including a plurality of blades arranged around an annular crown moving with the blades, which forms with its outer wall part of the outer envelope of the propulsion unit, the outer envelope being subjected to atmospheric conditions outside the propulsion unit, the turbomachine generating a flow of hot gases that exit via an annular hot vein, which is concentric with the moving annular crown, and defined for part of its surface by an inner wall of the moving annular crown. The deicing device includes: a mechanism transforming thermal energy into electrical energy, within the moving annular part; a mechanism transferring the generated electrical energy towards the rotor blades; and a mechanism transforming the electrical energy into thermal energy onto at least a part of the surface of the blades.