An ejector mechanism is provided for pulling an electrical mating end portion of an electronic device in a first direction away from an electrical connector that is provided on a circuit board. The ejector mechanism includes a base member adapted for retaining the electronic device thereon and having a rear end formed with an upwardly extending engaging flange that extends in a second direction transverse to the first direction, a cover member disposed above the base member and cooperating with the base member so as to confine the electronic device therebetween, and an elongated operating member extending in the second direction. The cover member has a pivot portion disposed above the engaging flange. The operating member is mounted pivotally on the pivot portion about a pivot axis, and has a hook projection which defines a downwardly opening engaging groove for receiving the engaging flange therein. The operating member is rotatable about the pivot axis to enable the hook projection to apply a pulling force in the first direction at the engaging flange, thereby resulting in corresponding movement of the base member in the first direction so as to disengage the electrical mating end portion of the electronic device from the electrical connector.