A portable electronic apparatus includes a first casing, a second casing, and an enhanced pivotal mechanism for folding/unfolding the second casing with respect to the first casing. The pivotal mechanism further includes a main pivot to pivot the first casing and the second casing; a combination constructed on the first casing and further including a first driving element driven by the main pivot, a first cam driven by the first driving element, and a first cover pivotally rotated by the first cam; and, another combination constructed on the second casing and further including a second driving element driven by the main pivot, a second cam driven by the second driving element, and a second cover pivotally rotated by the second cam.