Abstract: A gear transmission unit for an automatic transmission comprises: a single pinion type first planetary gear unit including a first sun gear, a first ring gear arranged concentrically with the first sun gear, and a first carrier retaining a pinion meshing with both the sun gear and the ring gear; a single pinion type second planetary gear unit including a second sun gear, a second ring gear arranged concentrically with the second sun gear and connected to the first carrier, and a second carrier retaining a pinion meshing with both the second sun gear and the second ring gear and connected to the first ring gear; and a double pinion type third planetary gear unit including a third sun gear connected to the first sun gear, a third ring gear arranged concentrically with the third sun gear, and a third carrier retaining both one pinion meshing with the third sun gear and another pinion meshing with the one pinion and the third ring gear. The first carrier is connected to the third ring gear.