Provided is a walking assist device capable of changing a battery to be used without decreasing a capability to assist walking A walking assist device comprises a leg attachment, a battery, and a controller. The leg attachment has an actuator for applying torque on a joint of one leg of a user. The battery supplies electric power to the actuator. The battery (a first battery) is configured by a plurality of battery cells being connected. A battery in which at least one battery cell is electrically separated from the first battery corresponds to a second battery. The controller changes a power source of the actuator from the first battery to the second battery while the other leg is making contact with ground.
