A vehicle height adjustment device includes a changer and a controller. The changer is configured to change a relative position of a body of a vehicle relative to an axle of a wheel of the vehicle. The controller is configured to control the changer to make the relative position a target value so as to control a vehicle height of the body. The controller is configured to control the changer to maintain the relative position when there is a possibility of a malfunction in a detector configured to detect a parameter for control.