An information processing device for readily entering a telephone number. A portable telephone with a jog dial (22) has a liquid crystal display (18) on which a telephone number display area (71) and a fixed cursor (72) is displayed. A generally circular line is displayed on the liquid crystal display (18) and numerals are displayed along the circular line. When the jog dial (22) is operated upward, the numerals along the circular line are moved downward. When the jog dial (22) is pressed, a numeral displayed in the cursor (72) is additionally displayed in the telephone number display area (71). The invention can be applied to a portable telephone.