PURPOSE: To improve respondence of a cluster system and reliability of the whole system by continuing data communication by another device even when a trouble occurred in one device.

CONSTITUTION: When an information control device 1 detects abnormality of the state of another information controlling device 7 side, the normal information control device 1 execute thereafter data communication in place of the information control device 7 in which abnormality occurred with other devices 10, 11 connected to signal transmission line of abnormal side, and prevents system down of the abnormal side. When another information control device 7 side is normal and the information control device 1 goes to abnormal, the normal information controlling device 7 makes data communication of abnormal side similarly. The state of abnormality includes excessive increase of information access process, communication fault etc.