A vehicle height adjustment device comprising: a changer (21, 22) configured to change a relative position of a body of a vehicle relative to an axle of a wheel (2, 3) of the vehicle; and a controller configured to control the changer to make the relative position a target value so as to control a vehicle height of the body of the vehicle, the controller being configured to control the changer to maintain the relative position irrespective of the target value when a decreasing malfunction occurs causing the vehicle height to decrease, wherein the changer comprises an actuator driven when supplied with a current and capable of changing the relative position, and wherein the controller comprises an actuator driver (733, 743) configured to drive the actuator, characterized in that the controller further comprises a relay (791, 792) configured to electrically connect the actuator driver and the actuator to each other and break a connection between the actuator driver and the actuator, a malfunction detector configured to detect the decreasing malfunction, and a relay driver configured to shut off the relay when the malfunction detector detects the decreasing malfunction, wherein the controller comprises a target current setter configured to set a target current supplied to the actuator in accordance with the target value of the relative position, and a current detector (734, 744) configured to detect a current supplied to the actuator, and wherein the malfunction detector is configured to determine that the decreasing malfunction has occurred when the target current set by the target current setter is a maintaining current for maintaining the relative position or an increasing current for increasing the relative position and when a detection value detected by the current detector is a decreasing current for decreasing the relative position, wherein the maintaining current is less than a first reference current, the increasing current is equal to or higher than the first reference current and less than a second reference current, which is set in advance to be higher than the first reference current, and the decreasing current is equal to or higher than the second reference current. a changer (21, 22) configured to change a relative position of a body of a vehicle relative to an axle of a wheel (2, 3) of the vehicle; and a controller configured to control the changer to make the relative position a target value so as to control a vehicle height of the body of the vehicle, the controller being configured to control the changer to maintain the relative position irrespective of the target value when a decreasing malfunction occurs causing the vehicle height to decrease, wherein the changer comprises an actuator driven when supplied with a current and capable of changing the relative position, and wherein the controller comprises an actuator driver (733, 743) configured to drive the actuator, characterized in that the controller further comprises a relay (791, 792) configured to electrically connect the actuator driver and the actuator to each other and break a connection between the actuator driver and the actuator, a malfunction detector configured to detect the decreasing malfunction, and a relay driver configured to shut off the relay when the malfunction detector detects the decreasing malfunction, wherein the controller comprises a target current setter configured to set a target current supplied to the actuator in accordance with the target value of the relative position, and a current detector (734, 744) configured to detect a current supplied to the actuator, and wherein the malfunction detector is configured to determine that the decreasing malfunction has occurred when the target current set by the target current setter is a maintaining current for maintaining the relative position or an increasing current for increasing the relative position and when a detection value detected by the current detector is a decreasing current for decreasing the relative position, wherein the maintaining current is less than a first reference current, the increasing current is equal to or higher than the first reference current and less than a second reference current, which is set in advance to be higher than the first reference current, and the decreasing current is equal to or higher than the second reference current.