PURPOSE: To diagnose the failure of electrical connection at the fitted time of male and female connectors and directly inform a user of the diagnosed result by series-connecting electric connectors, respectively provided at plural connectors, between a driving circuit and an informing means.

CONSTITUTION: Pairs of diagnostic electric connectors of connectors 8, 10, 12 are series-connected between the anode terminal of a light emission diode 22 and the collector terminal of a switching transistor 21. Accordingly, when a failure such as the severance of wire is generated to a detonator 9 in the case of all the connectors 8, 10, 12 being fitted normally, the switching transistor 21 is turned off. As a result, a current flows to the light emission diode 22 to inform the failure. Also in the case of failing to obtain electrical connection due to the non-fitted state of either one of the connectors 8, 10, 12, for instance, although no abnormality is generated to the detonator 9 or the like, the switching transistor 21 is turned off, so that the light emission diode 22 is lighted to give notice of the failure.