A hinge mechanism includes a shaft with shaft portion, shaft sleeve, first torque spring, and first sliding member. The shaft sleeve defines a through hole for the shaft portion extending through, a slot extending substantially parallel to the through hole, and forms hooks extending from two opposite sides of the slot. The first sliding member goes over the shaft sleeve, and the first torque spring includes a first end fixed to the shaft and a second end extending through the slot and then fixed to the first sliding member. The first torque provides torque to prevent the shaft sleeve from rotating to the shaft. When the first sliding member is moved along the shaft sleeve to compress the first torque spring, the torque can be adjusted.