The position of a smartphone placed on a touchscreen is determined. Smartphones are placed on a touchscreen of a table PC, and user interface images are displayed respectively around the smartphones to perform cooperation. The table PC displays a position pattern to determine the position of a smartphone being placed. The position pattern includes a pattern of two tones. A camera of the smartphone captures a blurred image of a predetermined location of the position pattern. The table PC identifies the position of the smartphone, from a tone value of the captured image received wirelessly from the smartphone. The table PC can thus determine the position of the smartphone without using special hardware.