The present invention provides a method and apparatus enabling multiple CPU systems to independently access a shared device, each of the multiple CPU systems having data I/O lines, a reset line, a clock line and the like without requiring an additional switching logic or circuit. The method of sharing the device among multiple CPU systems according to an embodiment of the present invention comprises setting interfaces of all the systems to a floating state, determining the status of a PIO indicating whether it is possible to access the device, and the status of the PIO to an access-disable state. The method of sharing the device among multiple CPU systems further comprises changing the status of an interface of a first system, which intends to access the device, so that communications can be made between the first system and the device, and transmitting and receiving data between the first system and the device.