A game apparatus includes a controller provided with an acceleration sensor for detecting accelerations on at least two axes orthogonal to each other. When playing a game, the controller is given a rotating operation so as to rotate around an axis orthogonal to the two axes. The accelerations on the two axes detected according to the rotating operation are converted into a point on a two-dimensional coordinate system. An angle of each converted point is calculated, and an angle change is also calculated. Based on the angle change corrected to change smoothly and a previous correction angle, a present correction angle is calculated. Game processing according to the correction angle is performed, and a game object is moved by an amount corresponding to the correction angle, for example.