A multi-speed transmission may include a first input shaft rotatable, a second input shaft rotatable coaxially with respect to the first input shaft, first clutch and second clutch respectively transmitting power from a driving source to the first and second input shafts, first output shaft and second output shaft parallel to the first and second input shafts, a plurality of odd-numbered gear-change gear trains provided between the first input shaft and the first output shaft and between the first input shaft and the second output shaft, a plurality of even-numbered gear-change gear trains provided between the second input shaft and the first output shaft and between the second input shaft and the second output shaft, and a reverse gear device installed in at least any one of the first and second output shafts, wherein the reverse gear device is configured as a planetary gear set.