A hinge mechanism includes a pivot shaft, a resilient member coiling around the pivot shaft, a first cam, a second cam, and a rolling assembly. The pivot shaft defines a through hole in a radial direction thereof. The first cam and the second cam are sleeved on the pivot shaft, the first cam defines two pairs of recesses at one end surface thereof, and the second cam defines a groove at one end surface thereof facing the first cam. The rolling assembly positioned between the first cam and the second cam includes a pin and two rolling bearings sleeved on opposite ends of the pin.