The present invention relates to a system and a method of preventing a contactor from being abnormally opened through a real-time detection of an operation, in which a contactor coil control unit, which applies an operation signal to a contactor coil (relay coil) that opens or connects contact points of a contactor (Relay), during a travelling of a vehicle applies an abnormal signal to the contactor coil by an external reason or a failure, the abnormal signal is detected in real time, so that it is possible to prevent the contact point of the contactor from being unintentionally opened by the abnormal signal, and particularly, it is possible to prevent an operating vehicle from being suddenly stopped by determining whether the vehicle actually travels based on a maintenance time of the abnormal signal and whether the abnormal signal is applied due to an actual failure of the contactor coil control unit.