A projection lens includes a lens barrel, at least one lens, a focus adjusting ring, a focus adjusting gear, and a driving module. The at least one lens is disposed in the lens barrel. The focus adjusting ring is disposed on the lens barrel. The focus adjusting gear is fixed on the focus adjusting ring. The driving module is connected with the focus adjusting gear. The driving module includes a motor, a motor gear, a limiter, and an elastic element. The motor has a rotating shaft. The motor gear is penetrated through by the rotating shaft and engages with the focus adjusting gear. The limiter is fixed on the rotating shaft. The elastic element is disposed between the limiter and the motor gear, wherein the limiter applies a normal force to the motor gear through the elastic element.