Portable electronic device with display modes for one-handed operation

A portable electronic device comprising:

• a case portion;
• a display portion provided on said case portion, said display portion having a rectangular display surface;
• an input portion that accepts input from a user;
• and
• a control portion,
• said input portion including a touch panel for detecting a touch position on said display surface, said touch panel being integral with said display portion,
• said display portion having, as display modes, a full-screen display mode in which an image is displayed over an entire surface of said display surface, a right-hand display mode in which a scaled-down display of an original image with a similarity shape is provided along a right side and a lower side of said display surface, and a left-hand display mode in which a scaled-down display of an original image with a similarity shape is provided along a left side and the lower side of said display surface, and
• when a prescribed operation is received by said input portion, said control portion switching a display mode of said display portion from said full-screen display mode to said right-hand display mode or said left-hand display mode.