An automatic back brushing massager has three brushes fixed on three planet gears. The three plant gears are positioned between a sun gear and an epicyclic gear and engage the sun and epicyclic gear in order to rotate synchroneously. The epicyclic gear also has a worm gear on an outer circumferential edge to engage a worm driven by a motor via a pair of bevel gears. The three brushes are then doubly rotated by said motor for brushing and massaging a person's back at the same time. This brushing and massaging is aided by the elasticity of coil springs set between brushes and the planet gears.