A palm rest with a detachable assembly mechanism attaches to a keyboard via the detachable assembly mechanism. The palm rest has a shell and at least one assembly mechanism. The shell forms a concave portion. The assembly mechanism has a base and a joint arm. The base is disposed in the concave portion of the shell. One end of the joint arm is pivotally mounted on the base so that the joint arm is rotatable and retractable in order to be received in the concave portion. The other end of the joint arm can extend outside the shell for assembly with the keyboard.