A device for switching an automatic transmission range includes an actuator, a detent mechanism driven by the actuator and engageable with concave portions, and a control unit. The control unit sets first and second positions of the detent mechanism as first and second target values for positions corresponding to first and second transmission ranges. The first position is detected when the detent mechanism is driven to a limit position, is driven by a first predetermined amount, moves toward a valley of a first concave portion without being driven by the actuator, and then stops naturally. The second position is detected when the detent mechanism is driven by a second predetermined amount to move away from the first target value, move toward a valley of a second concave portion without being driven by the actuator, and then stop naturally.