A portable electronic apparatus includes a first casing having a display surface in its surface, a second casing having a display surface in its surface, a coupling mechanism adapted to couple the first casing and the second casing to each other to take at least two states which are a closed state where the display surface in the first casing is covered with a rear surface of the second casing and also the display surface in the second casing is exposed, and an open state where the second casing has been moved with respect to the first casing from the closed state, and the display surfaces in both the casings are exposed in the same plane.