A six speed M/T includes four shafts, which are an input shaft A1, a first intermediate shaft A2, a second intermediate shaft A3, and an output shaft A4, those being parallel to one another. A single drive gear G46i is used as both a fourth-speed drive gear and a sixth-speed drive gear. The number of gear teeth of a second final drive gear Gfi2 is greater than that of a first final drive gear Gfi1. A third-speed driven gear G3o, a fourth-speed driven gear G4o, a first-speed driven gear G1o, and a second-speed driven gear G2o are arranged to the shaft A2 in this order from the side close to an engine E/G, and a fifth-speed driven gear G5o, a sixth-speed driven gear G6o, and a reverse driven gear GRo are arranged to the shaft A3 in this order from the side close to the engine E/G.