A vehicle steerable by movement of the center of gravity has an auxiliary wheel. A left drive wheel is driven by a left rotary driver. A right drive wheel is driven by a right rotary driver. A gravity center position calculator calculates a position of the center of gravity of a driver on a steering step board based on a detection signal from a load detection module detecting a load distribution of the driver. A travel controller has a first control mode controlling rotary drive of the left and right rotary drivers to achieve straight forward travel or turning. The travel controller also has a second control mode controlling the rotary drive of the left and right rotary drivers to achieve straight forward travel, turning or straight backward travel based on the position of the center of gravity. A driver input operation device can be used to select either the first or the second control mode.