Device for back massage, in which each brush is removable, the face opposite the brush face having a prismatic axle for transmitting the action of the motor system, and in which the support has, for each brush, a prismatic seat combined with the aforementioned prismatic axle, at least one of the walls of the prism of the axle or of the seat having, moreover, a recess perpendicular to the wall to receive a part driven by a spring placed, in turn, inside a recess situaded in a correspodning face of the seat or axle and in which each axle has, in turn, on the face opposite the brush face, a groove around said axle to receive a corresponding wall located on the support.