A game apparatus calculates a first evaluation value based on the difference between the time when the load value detected by a load controller becomes the maximum and the time when the velocity of the center of gravity, which represents the velocity of movement of the position of the center of gravity, becomes the maximum. The game apparatus calculates a second evaluation value based on the velocity of load, which represents the degree of increase in the load in a predetermined time period, and the velocity of the center of gravity. The game apparatus calculates a third evaluation value based on the path of the position of the center of gravity. The game apparatus calculates the amount of slice based on the first through third evaluation values.