The present invention provides a portable electronic device. The device includes a first controller, a second controller, a mode switch unit, and a main controller. The mode switch unit is for a user to operate thereby generating a mode switch instruction. The main controller is for switching a work mode according to the mode switch instruction from the mode switch unit. When the mode switch unit generates a first mode switch instruction, the device enters a common work mode whereby the main controller activates the first controller and the second controller to be on standby; and when the mode switch unit generates a second mode switch instruction, the device enters a single work mode whereby the main controller activates only one of the first controller and the second controller to be on standby.