The invention relates to an explosion initiating device capable of preventing accidental explosion initiation for wells. An alternating current of 220V is divided into two circuits to be connected to a direct-current electric source U1; the direct-current electric source U1 is divided into three circuits, wherein one circuit of the direct-current electric source U1 is sequentially connected with a pointer voltmeter U2, an explosion initiating relay U3, a bidirectional pointer ammeter U4, a polarity switching relay U5, a circuit break switch U6, a short-circuiting switch U7 and a connector U8, another circuit of the direct-current electric source U1 is sequentially connected with a key switch U9, a cable polarity select switch U10, a positive electricity explosion initiating switch U11 and a negative electricity explosion initiating switch U12, and the last circuit of the direct-current electric source U1 is connected to a voltage regulating knob U13; the explosion initiating relay U3 is separately connected with the positive electricity explosion initiating switch U11 and the negative electricity explosion initiating switch U12; and a processor U14 is separately connected with the cable polarity select switch U10, the positive electricity explosion initiating switch U11 and the negative electricity explosion initiating switch U12. According to the explosion initiating device disclosed by the invention, each knob of the cable polarity select switch corresponds to the polarity status indication of downhole detonators, and a positive electricity explosion initiating button and a negative electricity explosion initiating button are independently arranged, so that the explosion initiating safety is high; and the problems of misoperation, accidental action, and accidental explosion initiation of perforation caused by residual high voltage of cables can be solved.