To provide a rearing simulation system in which a virtual creature can be made to take part in various events on a high quality screen without damaging portability so that a player can take care of the virtual creature anytime as required.

A game machine has a central unit 10 and a portable electronic device 19 (20) freely attachably and detachably connected to this central unit 10. The portable electronic device 19 (20) has a rearing means (microcomputer 31) for rearing the virtual creature and a transmitting means for transmitting data on the reared virtual creature to the central unit. The central unit 10 has a storage means (ROM 53) for storing a program concerning an event and the virtual creatures of a plurality of kinds to take part in the relevant event and further has a participation means (controller 31) for specifying a correspondent virtual creature on the basis of the data on the virtual creature received from the portable electronic device 19 (20), reading this specified virtual creature from the storage means (ROM 53) and making this creature take part in the event.