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 of the vehicle; and a controller (70, 780) 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 being configured to control the changer to maintain the relative position when there is a possibility of a malfunction in a detector (734, 744) configured to detect a parameter for control, wherein the changer comprises an actuator (300, 302) driven when supplied with a current and capable of changing the relative position, and wherein the parameter is a value of the current supplied to the actuator, the controller being configured to control the current supplied to the actuator to maintain the relative position when there is the possibility, and comprising a relative position detector (281, 282) configured to detect the relative position, wherein the controller further comprises a target current setter (731, 741) configured to set a target current supplied to the actuator in accordance with a target value of the relative position, characterized in that when a detection value detected by the detector is a maintaining current for maintaining the vehicle height, which is less than an increasing current for increasing the relative position, in a case where the target current set by the target current setter is the increasing current and when a period of time in which the relative position detected by the relative position detector keeps decreasing is a predetermined period of time, the controller is configured to determine that there is the possibility. a changer (21, 22) configured to change a relative position of a body of a vehicle relative to an axle of a wheel of the vehicle; and a controller (70, 780) 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 being configured to control the changer to maintain the relative position when there is a possibility of a malfunction in a detector (734, 744) configured to detect a parameter for control, wherein the changer comprises an actuator (300, 302) driven when supplied with a current and capable of changing the relative position, and wherein the parameter is a value of the current supplied to the actuator, the controller being configured to control the current supplied to the actuator to maintain the relative position when there is the possibility, and comprising a relative position detector (281, 282) configured to detect the relative position, wherein the controller further comprises a target current setter (731, 741) configured to set a target current supplied to the actuator in accordance with a target value of the relative position, characterized in that when a detection value detected by the detector is a maintaining current for maintaining the vehicle height, which is less than an increasing current for increasing the relative position, in a case where the target current set by the target current setter is the increasing current and when a period of time in which the relative position detected by the relative position detector keeps decreasing is a predetermined period of time, the controller is configured to determine that there is the possibility.