MOBILE ELECTRONIC DEVICE

PROBLEM TO BE SOLVED: To provide a mobile electronic device allowing an optional selection between an operation input by a back operation and a keyboard input.SOLUTION: A mobile phone terminal 1 comprises mode changeover means 40 and a state detection sensor 50 so as to change an operation mode of the mobile phone terminal 1. The mode changeover means 40 is a computer having a changeover program installed therein and executing prescribed processing according to a signal input from the state detection sensor 50 and the changeover program. The state detection sensor 50 is a sensor for detecting a current state of the mobile phone terminal 1 and employs, for example, an angle sensor which detects a relative angle formed by first and second housings around X axis.