A current detecting mechanism according to this invention includes a direct current shunt having a plurality of resistor members with high resistivity to output an electric potential difference across the resistor members, proportional to a current flowing through an electric load side terminal, as a voltage signal, and a hall sensor assembly having a pair of magnetic cores installed to face each other with an air gap therebetween, and a hall sensor to output an output voltage according to a magnetic flux induced in proportion to a current flowing through a load side terminal, without being connected with the direct current shunt, of load side terminals.