A transmission for a vehicle may include a first input shaft continuously receiving power from an engine, a second input shaft selectively receiving power from the engine, a first output shaft and a second output shaft disposed in parallel with the first input shaft and the second input shaft, an initial shift device including a plurality of driving gears on the second input shaft, a plurality of driven gears on the first output shaft and the second output shaft for making a series of gear shift ranges, and a plurality of synchronizers selectively making a predetermined gear shift range of the gear shift ranges made by the driving gears and the driven gears, a duplicate shift device configured to make duplicate gear shift ranges, a first output gear disposed on the first output shaft to draw power from the first output shaft, and a one-way clutch.