A joint mechanism is for a robot. The joint mechanism includes a base; a first drive device mounted on the base including a first drive shaft; a second drive device including a second drive shaft; a joint body defining a plurality of toothed grooves and a guiding groove. A sliding board mounted on first drive shaft, the sliding board slidably located in the guiding groove to guide the joint body to swing relative to the base. A gear mounted on the second drive shaft, the gear meshes with the toothed grooves; a limiting assembly for rotatably mounting the joint body on the base. When the first drive device is started, the first drive shaft is rotated to drive the joint body rotating around the first drive shaft; when the second drive device is started, the second drive shaft is rotated to drive the gear rotating so the joint body swings relative to the base.