The present invention is directed to a transmission capable of minimizing the number of speed-change driven gears on a first countershaft to ensure a layout space in an engine compartment of a vehicle, and reducing a driving torque to be applied to a second countershaft to facilitate downsizing of the transmission. In the transmission, the first countershaft 2 is arranged at a position above an input shaft 1, and a first-speed driven gear 14 and a second-speed driven gear 24 are provided on the first countershaft 2.