A transmission for a vehicle which can be applied to a shift mechanism where a shaft itself is rotated and having a simple configuration and axial miniaturization. A transmission for a vehicle in which a plurality of transmission shafts are provided each of which supports a plurality of transmission gears in a row and are arranged in parallel so that mutually corresponding transmission gears are engaged and transmission gears rotating in synchronization with the hollow shaft are selectively switched. Every transmission shaft is provided with a clutch mechanism provided between the hollow shaft and each transmission gear for fitting the hollow shaft and each transmission gear or releasing the fitting and a clutch actuator housed in the hollow shaft and the clutch mechanism selectively fits any transmission gear to the hollow shaft according to the axial position of the clutch actuator.