To make operation simple and joyful by easily associating the operation to an input device with movement of a display object in an image control system.

When a user grabs a first leg-shaped operating part SR of the input device and turns the operating part 3R, a resistance value of a potentiometer 4R changes in accordance with a turned angle θ of the first leg-shaped operation part 3R. An analog signal of a value corresponding to the resistance value is converted into a digital signal by an A/D converter, and the digital signal is inputted to an image controller. Also, when the user grabs a second leg-shaped operating part 3L of the input device and turns the operating part 3L, a resistance value of a potentiometer 4L changes in a similar manner. The image controller moves a right leg of the display object in accordance with these signals and displays the right leg.