A housing of a game controller is capable of being held with one hand of a player. A direction instruction section is provided in the housing for performing a direction instruction input. Movement detection means is means for detecting movement of the housing. Movement direction control means of a game apparatus is means for determining a movement direction of an object, which appears in a virtual game world, in accordance with an operation of the direction instruction section. Posture control means is means for determining a posture of the object in the virtual game world in accordance with detection by the movement detection means.