In an information terminal apparatus 1 having a thin housing structure including at least a display (not shown), the information terminal apparatus being driven by batteries 102, a battery pack 10 to accommodate therein the batteries 102 includes a rotary support mechanism for rotating the battery pack 10 about the intermediate portion of the rear wall side 1d of this display so that the battery pack becomes freely openable and closable from the lower portion of the rear wall side 1d of this display, wherein the rotated battery pack 10 is used as a stand to enable this display to rise to the erect position and the battery pack 10 is directly exposed to the air.