Polishing and/or sanding head, comprising: - a primary disc which is axially hollow; - a rotating shaft which is received in the internal cavity of the primary disc and rotatably supported by the latter, said rotating shaft being configured in such a way as to receive a rotary motion about an axis coincident to the axis of the primary disc by means of a power take-off external to the head; and - a body which is radially external and coaxial with respect to the rotating shaft, said body being rotatably supported by said primary disc; characterized by also comprising a planetary gear transmission which is adapted to transmit the rotational motion of the rotating shaft to the body, said transmission comprising: - a sun gear which is integral in rotation with the rotating shaft and has an external toothing facing the body; - a ring gear which is integral in rotation with the body and has an internal toothing facing the axis of the primary disc; and - at least one planet gear which is supported by the primary disc so as to be rotatable about a secondary axis (y) which is parallel and not coincident with the axis of the primary disc, said planet gear being placed in an intermediate position between the sun gear and the ring gear in such a way as to engage both and transmit a rotary motion from said sun gear to said ring gear; the head further comprising a first support for a treatment means which is integral in rotation with the rotating shaft and has an exposed surface adapted to form or support a means suitable for polishing or sanding a surface to be treated, and a second support for a treatment means which is integral in rotation with the body and has an exposed surface adapted to form or support a means suitable for polishing or sanding said surface to be treated, said first and second supports for a treatment means (24, 26) being configured, respectively, as a circular element and an annular element that are concentric to each other, the second support for a treatment means being designed to rotate in the opposite direction with respect to the direction of rotation of the first support for a treatment means. - a primary disc which is axially hollow; - a rotating shaft which is received in the internal cavity of the primary disc and rotatably supported by the latter, said rotating shaft being configured in such a way as to receive a rotary motion about an axis coincident to the axis of the primary disc by means of a power take-off external to the head; and - a body which is radially external and coaxial with respect to the rotating shaft, said body being rotatably supported by said primary disc; characterized by also comprising a planetary gear transmission which is adapted to transmit the rotational motion of the rotating shaft to the body, said transmission comprising: - a sun gear which is integral in rotation with the rotating shaft and has an external toothing facing the body; - a ring gear which is integral in rotation with the body and has an internal toothing facing the axis of the primary disc; and - at least one planet gear which is supported by the primary disc so as to be rotatable about a secondary axis (y) which is parallel and not coincident with the axis of the primary disc, said planet gear being placed in an intermediate position between the sun gear and the ring gear in such a way as to engage both and transmit a rotary motion from said sun gear to said ring gear; the head further comprising a first support for a treatment means which is integral in rotation with the rotating shaft and has an exposed surface adapted to form or support a means suitable for polishing or sanding a surface to be treated, and a second support for a treatment means which is integral in rotation with the body and has an exposed surface adapted to form or support a means suitable for polishing or sanding said surface to be treated, said first and second supports for a treatment means (24, 26) being configured, respectively, as a circular element and an annular element that are concentric to each other, the second support for a treatment means being designed to rotate in the opposite direction with respect to the direction of rotation of the first support for a treatment means.