A processing apparatus includes a plurality of operation units each of which performs a given operation for an input operand in accordance with an operating instruction and outputs an exception flag when a result of the operation is false, a first network which connects the storage unit which stores the operand and the operation units, a second network which connects the operation units and the storage unit, and a defect sensor which receives the exception flag from each of the operation units to sense an operation unit from which the exception flag is generated with high frequency. The apparatus further includes a logic unit controller which controls the first network and the second network to disconnect the operation unit from a system, and causes another operation unit to perform an operation assigned to the disconnected operation unit again.