A component in a horizontal direction (the x-axis component) of a movement amount first acquired after a pointing device is reset and a component in a vertical direction (the y-axis component) are compared, a movement input is regarded as provided only in the horizontal direction in case the absolute value of the x-axis component is larger than the absolute value of the y-axis component, a movement input is regarded as provided only in the vertical direction in case the absolute value of the y-axis component is larger than the absolute value of the x-axis component, a movement input is regarded as provided in the same direction unless the ratio of components of movement inputs is greatly changed subsequently, and continuous movement inputs in the same direction are facilitated.