A cellular phone has a three-stage stacked structure including a ten-key case of a lower stage, a full-key case of a middle stage and a display case of an upper stage. When the cellular phone is in call style, the ten-key case is slid in the longitudinal direction to expose a dial key. When the cellular phone is in keyboard style, the display case is turned on its rotating shaft above the full-key case to expose a full keyboard. The rotating shaft is located in the middle of the display case and close to a long side thereof.