PURPOSE: To allow the inspecting device to judge an interruption mode automatically and to also control the signal direction of an interruption terminal by masking every interruption request terminal in interruption mode through operator's switch operation.

CONSTITUTION: An interruption control switch 22 which masks an interruption request from a circuit board 6 to be inspected, level by level, and a signal direction control switch 22' which controls the direction of a signal in two directions of a specific interruption terminal are provided on a repeater (POD)2. Then, a necessary interruption request signal among signals from the circuit board 6 to be indpected is gated with a signal from a switch 22 and outputted as it is, and the remaining interruption request signals are gated with the signal from the switch 22 and then outputted through a tristate buffer whose signal direction is controlled with the switch 22'. Consequently, such trouble that a gate output and processor output short-circuit each other never occurs and proper interruption control is performed.