Am image generating system and program which can generate an image in which the change of state in an object propagate with less amount of data and reduced load in computation is provided. The image generating system generates an aggregate object (600) which is formed by a plurality of elemental objects. Each of the elemental objects (610-1 to 610-9) has means (620-1 to 620-9) for holding its own state in its own state buffer (622-1 to 622-9), means (640-1 to 640-9) for monitoring the other elemental objects belonging to the same aggregate object, and means (650-1 to 650-9) for changing the state of that elemental object when the states of the other elemental objects having a predetermined relationship relative to the elemental object are changed.