1. A game device, comprising: a display unit for displaying a game screen including a moving image moving within the game screen and a trajectory image for indicating a reference trajectory; a designated position obtaining unit for obtaining a position within the game screen, the position being designated by a player; a first moving image control unit for moving the moving image from a given initial position toward a start point of the reference trajectory; a second moving image control unit, in the case where the moving image reaches the start point of the reference trajectory, for moving the moving image along the reference trajectory; a determination unit for determining whether or not the position obtained by the designated position obtaining unit is located within an area based on a position of the moving image during a period when the moving image is moving along the reference trajectory; and a game processing unit for carrying out a game process based on a result of determination made by the determination unit.