In a multi-computer system having a plurality of computers, an input/output device configuration definition table and an input/output device configuration reference table are adapted to be collectively managed. A configuration management program manages the configuration definition of all input/output devices of a plurality of computers by using the input/output device configuration definition table, and generates a changed data file when an input/output device configuration is changed. Dynamic system alteration is effected by changing the contents of the input/output device configuration reference table stored in a shared memory, in accordance with the changed data file. The input/output device configuration definition table and the input/output device configuration reference table each have an input/output device information part and an input/output device connection information part arranged in a matrix form to allow addition/deletion of an input/output device and a computer.