According to an embodiment of the present disclosure, an apparatus of preventing a malfunction of a circuit breaker may include a circuit breaker and a variable resistor installed on a distributing board, the variable resistor being disposed outside the circuit breaker separately from the circuit breaker, wherein the variable resistor is connected in parallel to an anti-pumping auxiliary relay RW, and total resistance of the anti-pumping auxiliary relay RW and the variable resistor connected in parallel to each other is less than resistance of the anti-pumping auxiliary relay RW.