PURPOSE: To easily restore one application kit which becomes inoperable by carrying on the operation by another application kit until the former application kit recovers even if the application kits is disabled to operate.

CONSTITUTION: A kit-down monitor part 7 monitors the operation states of plural application kits in operation at all times and detects one application kit being disabled to operate in the case that either of application kits is inoperable. An SK 13 disconnects the application kit whose inoperativeness is confirmed by the kit-down monitor part 7 and an input buffer 8 stores data which should be inputted to the pertinent application kit in the inoperable state. When the application kit in the inoperable state recovers, a BASE 4 makes the application kit in turn perform processing of the data stored in the input buffer 8 in order.