INFORMATION PROCESSOR

PROBLEM TO BE SOLVED: To make it possible to use a highly reliable information processor also as normal information processor by adding a simple circuit. SOLUTION: Each of a master processor 10-1 and slave processors 10-2, 10-3 is provided with plural input buffers 41-1 to 41-3 for taking information on a bus 20 inside, an input switching part 51 for outputting a signal E11 passed through the whole input buffers 41-1 to 41-3 in a high reliability mode and outputting a signal E10 passed through only one input buffer 41-1 in a normal mode, a processor number switching part for outputting the common processor number in the high reliability mode and outputting the proper processor number in the normal mode and a signal invalidating circuit 61 for validating existence information E30 and master information E31 in the high reliability mode and invalidating these information E30, E31 in the normal mode.