Abstract: A planetary gear device having a first and a second single-pinion planetary gear unit and a third double-pinion planetary gear unit, which are coaxially disposed so as to provide different speed reduction ratios. The three gear units have respective first, second and third sun gears, respective first, second and third ring gears, and respective first, second and third carriers rotatably supporting planetary pinions. The first and second sun gears are fixed together or selectively connectable to each other, and the first carrier, second ring gear and third carrier are fixed together or selectively connectable to each other. Further, the second carrier and the third sun gear are fixed together or selectively connectable to each other. The present arrangement allows shifting operations of the gear device, without concurrent disengagement and engagement of different clutches.