A trip control circuit for a circuit breaker, the trip control circuit comprising: a current transformer that has a ring-shaped core allowing a circuit to pass through and a secondary coil wound around the core for detecting a current flowing on the circuit and providing a current detection signal; an oscillation circuit section that is configured to apply an electrical signal to the secondary coil of the current transformer to increase a slope of a hysteresis loop of the current transformer to allow the secondary coil to detect a DC current, as well as an AC current, flowing on the circuit, wherein the electrical signal applied by the oscillation circuit section is configured with a square wave signal or a sine wave signal; and a trip determining circuit section that is configured to compare a current value indicated by the current detection signal having an AC component and a DC component output from the secondary coil of the current transformer with a predetermined reference current value, and to output a trip control signal when the current value indicated by the current detection signal exceeds the reference current value; characterized in that the trip determining circuit section is configured: to determine a current value of the current flowing on the circuit on the basis of the current detection signal, and, when the trip determining circuit section determines that the current value indicated by the current detection signal is a waveform indicating DC characteristics or a waveform in which a DC and a AC are mixed, to determine a waveform of the electrical signal to be supplied to the secondary coil by transmitting a selection control signal through the oscillation circuit section, wherein the trip determining circuit section is adapted to detect, as a result of the current detection signal provided by the secondary coil, based on whether halves of one cycle waveform are asymmetric or symmetric with respect to each other, whether the waveform of the electric signal of the current flowing on the circuit is a mixed current in which the AC component and the DC component are mixed or a pure AC. a current transformer that has a ring-shaped core allowing a circuit to pass through and a secondary coil wound around the core for detecting a current flowing on the circuit and providing a current detection signal; an oscillation circuit section that is configured to apply an electrical signal to the secondary coil of the current transformer to increase a slope of a hysteresis loop of the current transformer to allow the secondary coil to detect a DC current, as well as an AC current, flowing on the circuit, wherein the electrical signal applied by the oscillation circuit section is configured with a square wave signal or a sine wave signal; and a trip determining circuit section that is configured to compare a current value indicated by the current detection signal having an AC component and a DC component output from the secondary coil of the current transformer with a predetermined reference current value, and to output a trip control signal when the current value indicated by the current detection signal exceeds the reference current value; to compare a current value indicated by the current detection signal having an AC component and a DC component output from the secondary coil of the current transformer with a predetermined reference current value, and to output a trip control signal when the current value indicated by the current detection signal exceeds the reference current value; characterized in that the trip determining circuit section is configured: to determine a current value of the current flowing on the circuit on the basis of the current detection signal, and, when the trip determining circuit section determines that the current value indicated by the current detection signal is a waveform indicating DC characteristics or a waveform in which a DC and a AC are mixed, to determine a waveform of the electrical signal to be supplied to the secondary coil by transmitting a selection control signal through the oscillation circuit section, wherein the trip determining circuit section is adapted to detect, as a result of the current detection signal provided by the secondary coil, based on whether halves of one cycle waveform are asymmetric or symmetric with respect to each other, whether the waveform of the electric signal of the current flowing on the circuit is a mixed current in which the AC component and the DC component are mixed or a pure AC. to determine a current value of the current flowing on the circuit on the basis of the current detection signal, and, when the trip determining circuit section determines that the current value indicated by the current detection signal is a waveform indicating DC characteristics or a waveform in which a DC and a AC are mixed, to determine a waveform of the electrical signal to be supplied to the secondary coil by transmitting a selection control signal through the oscillation circuit section, wherein the trip determining circuit section is adapted to detect, as a result of the current detection signal provided by the secondary coil, based on whether halves of one cycle waveform are asymmetric or symmetric with respect to each other, whether the waveform of the electric signal of the current flowing on the circuit is a mixed current in which the AC component and the DC component are mixed or a pure AC.