A range-finding device includes: a light emitting unit that continuously emits measurement light to be used for distance measurement toward a measurement target object; a light-receiving unit that receives reflected light reflected by the measurement target object; a calculation unit that repeatedly calculates a distance to the measurement target object over predetermined time intervals by using the reflected light; a display unit at which an update of the distance is displayed each time the distance is calculated by the calculation unit; and a display update control unit that prohibits the update of the distance on display at the display unit and sustains the display of the previously calculated distance at the display unit according to a change in the most recently calculated distance calculated most recently by the calculation unit relative to the previously calculated distance having been calculated previously by the calculation unit.