A cooking hob with rotary blade driving means, of the type comprising: a continuous glass or glass ceramic support plate provided with a treatment area; and rotary blade driving means comprising a lower magnetic coupling member rotatably arranged in said treatment area below the support plate and a drive motor operatively connected for rotating said lower magnetic coupling member; activation/deactivation means for substantially activating and deactivating the magnetic field exerted by the lower magnetic coupling member through the support plate, characterized in that said activation/deactivation means comprise: position changing means for moving the lower magnetic coupling member between an operative position, in which the lower magnetic coupling member is close enough to the support plate to magnetically transmit torque to an upper magnetic coupling member connected to rotary blades installed in a cooking vessel located on the treatment area of the support plate, and an inoperative position, in which the lower magnetic coupling member is far enough from the support plate so as to not transmit said torque; or shielding means for moving a shield element between an inactive position, in which said shield element is separated from the lower magnetic coupling member to allow it to magnetically transmit torque to an upper magnetic coupling member connected to rotary blades installed in a cooking vessel located on the treatment area of the support plate, and an active position, in which the shield element is arranged between the support plate and the lower magnetic coupling member to prevent transmitting said torque, a continuous glass or glass ceramic support plate provided with a treatment area; and rotary blade driving means comprising a lower magnetic coupling member rotatably arranged in said treatment area below the support plate and a drive motor operatively connected for rotating said lower magnetic coupling member; activation/deactivation means for substantially activating and deactivating the magnetic field exerted by the lower magnetic coupling member through the support plate, characterized in that said activation/deactivation means comprise: position changing means for moving the lower magnetic coupling member between an operative position, in which the lower magnetic coupling member is close enough to the support plate to magnetically transmit torque to an upper magnetic coupling member connected to rotary blades installed in a cooking vessel located on the treatment area of the support plate, and an inoperative position, in which the lower magnetic coupling member is far enough from the support plate so as to not transmit said torque; or shielding means for moving a shield element between an inactive position, in which said shield element is separated from the lower magnetic coupling member to allow it to magnetically transmit torque to an upper magnetic coupling member connected to rotary blades installed in a cooking vessel located on the treatment area of the support plate, and an active position, in which the shield element is arranged between the support plate and the lower magnetic coupling member to prevent transmitting said torque, position changing means for moving the lower magnetic coupling member between an operative position, in which the lower magnetic coupling member is close enough to the support plate to magnetically transmit torque to an upper magnetic coupling member connected to rotary blades installed in a cooking vessel located on the treatment area of the support plate, and an inoperative position, in which the lower magnetic coupling member is far enough from the support plate so as to not transmit said torque; or shielding means for moving a shield element between an inactive position, in which said shield element is separated from the lower magnetic coupling member to allow it to magnetically transmit torque to an upper magnetic coupling member connected to rotary blades installed in a cooking vessel located on the treatment area of the support plate, and an active position, in which the shield element is arranged between the support plate and the lower magnetic coupling member to prevent transmitting said torque,