A twin-clutch manual gearbox has a first input shaft and a second input shaft to which engine rotation is selectively input via individual clutches. The second input shaft is rotatably fitted onto the first input shaft so that the first input shaft protrudes from an end of the second input shaft farthest from the engine. First gearsets are located between the protruding end of the first input shaft and a layshaft located between the first and second input shafts. Second gearsets are located between the second input shaft and the layshaft. The second gearsets are positioned such that the gearset of the lowest gearbox speed which is capable of providing a bearing retaining space between the first input shaft and the second input shaft is positioned farthest from the engine, and the gearset of the highest gearbox speed is positioned closest to the engine.