The composite planetary gear apparatus according to the present invention can bring about an advantageous effect to prevent fuel efficiency from being lowered stemming from the increased stirring loss of oil. The apparatus comprises a first planetary gear assembly 11 having a sun gear S1, pinion gears P1, and a ring gear R1, and a second planetary gear assembly 12 having a sun gear S2, pinion gears P2, and a ring gear R2. The ring gears R1 and R2 surround the pinion gears P1 and P2 and are combined together to integrally form a counter drive gear 13. The counter drive gear 13 is formed with a plurality of through bores 13c each having an inner end opened at a closed space defined by the first and second planetary gear assemblies 11 and 12, and an outer end opened at an outer space surrounding the counter drive gear 13.