PURPOSE: To perform high speed diagnosis on a logical circuit integrated in a large scale, by dividing a combination circuit into blocks each capable of performing a single test.

CONSTITUTION: On the basis of the data read from the logical circuit data storing means 59 of a combination circuit, the combination circuit is divided into blocks each capable of performing a single test by a block dividing device 60 so that the output of one gate is not connected to two or more gate inputs in the blocks, while a block output is one and the number of elements become max. The movement of a stage having an integrated circuit 52 to be inspected mounted thereon is controlled corresponding to the division result through a stage control unit 54 and electron beam or laser beam 54 is allowed to irradiate from an electron beam tester or laser prober 51 at every block according to an order to perform diagnosis. The number of measuring places are reduced by block diagnosis easy to diagnose by a probe and high speed diagnosis can be conducted on a logical circuit integrated in a large scale.