A cable management device includes a first cable management arm, a second cable management arm and an auxiliary member. The second cable management arm is movable relative to the first cable management arm. The auxiliary member is extendable and retractable relative to one of the first cable management arm and the second cable management arm. When the auxiliary member is moved relative to the one of the first cable management arm and the second cable management arm, a length direction of the auxiliary member is parallel to a length direction of the one of the first cable management arm and the second cable management arm, and the auxiliary member is movable along the length direction of the one of the first cable management arm and the second cable management arm.