A system comprising an electronic circuit breaker and an operation test device, wherein the electronic circuit breaker, comprises: a switching contact, inserted in an alternating current electric path, on which a switching operation is carried out by a tripping coil; a rectifier circuit, connected to a secondary side of a current transformer that detects a current flowing into the alternating current electric path, that converts a secondary side output current into a unidirectional current; voltage restricting means; a current detection resistor, connected to the rectifier circuit, that detects a current of the alternating current electric path; a determination circuit, that is connected via the voltage restricting means, monitors a voltage generated by a current flowing into the current detection resistor, and causes the switching contact to open via the tripping coil when the monitored voltage exceeds a predetermined threshold; and a testing detection resistor, connected to the current detection resistor, that is connected in series to an input terminal of the determination circuit; wherein the operation test device, when the alternating current electric path is not energized, inputs a constant current into a latter stage of the rectifier circuit from an exterior via a connection connector, inputs a test signal into the testing detection resistor, and carries out a tripping operation test on the circuit breaker, characterized in that the electronic circuit breaker further comprises: a first switching element connected to an output side of the rectifier circuit; a second switching element that isolates a load from the output side of the rectifier circuit; voltage switching means, connected to a control terminal of the second switching element, that switches an output voltage of a power supply circuit connected to a thyristor connected in series to the tripping coil; and a voltage monitoring circuit, connected via the voltage restricting means, that carries out a control of the first switching element; wherein the voltage restricting means are connected to an output side of the second switching element; wherein the current detection resistor detects a current of each phase of the alternating current electric path; and wherein the determination circuit is formed of an instantaneous trip determination circuit and a time-limit trip determination circuit. a switching contact, inserted in an alternating current electric path, on which a switching operation is carried out by a tripping coil; a rectifier circuit, connected to a secondary side of a current transformer that detects a current flowing into the alternating current electric path, that converts a secondary side output current into a unidirectional current; voltage restricting means; a current detection resistor, connected to the rectifier circuit, that detects a current of the alternating current electric path; a determination circuit, that is connected via the voltage restricting means, monitors a voltage generated by a current flowing into the current detection resistor, and causes the switching contact to open via the tripping coil when the monitored voltage exceeds a predetermined threshold; and a testing detection resistor, connected to the current detection resistor, that is connected in series to an input terminal of the determination circuit; a first switching element connected to an output side of the rectifier circuit; a second switching element that isolates a load from the output side of the rectifier circuit; voltage switching means, connected to a control terminal of the second switching element, that switches an output voltage of a power supply circuit connected to a thyristor connected in series to the tripping coil; and a voltage monitoring circuit, connected via the voltage restricting means, that carries out a control of the first switching element; wherein the voltage restricting means are connected to an output side of the second switching element; wherein the current detection resistor detects a current of each phase of the alternating current electric path; and wherein the determination circuit is formed of an instantaneous trip determination circuit and a time-limit trip determination circuit.