A vehicle transmission includes a main transmission, a sub-transmission, a sub-transmission shift position sensor, and a map switching device. The main transmission is an automatic transmission configured to perform gear shifting according to a gear shift map selected between a first gear shift map and a second gear shift map in accordance with a throttle opening degree and a vehicle speed. The sub-transmission is configured to change rotational speed of rotational drive force output from the main transmission by manually selecting a sub-transmission gear position between a drive position and a low position having a reduction ratio larger than a reduction ratio of the drive position. The map switching device is configured to perform switching between the first gear shift map and the second gear shift map in accordance with sensing signals from the sub-transmission shift position sensor.