A game apparatus includes an LCD. An on-earth object existing in a virtual game space is reproduced on the LCD from a viewpoint of capturing ahead of a flying object moving in the virtual game space. A velocity parameter and a direction parameter which defines the movement parameter of the flying object are changed in response to a button operation by a player. An altitude where the flying object will reach after a lapse of a time T (T>0) is predicted on the basis of the movement parameter of the flying object. A height above the sea level of the on-earth object existing in the predicted point is detected with reference to map data. Difference information indicating a difference between the detected height above the sea level of the on-earth object and altitude of the flying object is output to the player through the LCD.