PROBLEM TO BE SOLVED: To provide a direct current detection apparatus capable of calibrating sensor sensitivity to detect a current to be measured with high accuracy even under circumstances where a use environmental temperature varies.SOLUTION: A flux gate type current sensor includes: a flux gate current sensor that has a magnetic material core for forming a closed magnetic circuit, an excitation winding wound around the magnetic material core, and a detection winding wound around the magnetic material core, and in which a current line to be measured penetrates the magnetic material core; an AC exciting part that generates an excitation magnetic field by energizing the excitation winding; a filter part that extracts only the second harmonic component of the excitation magnetic field from an output voltage waveform of the detection winding; an arithmetic processing part that calculates a current value flowing through the current line to be measured on the basis of the output of the filter part; and an integration processing part and others that perform integration processing of the output voltage waveform of the detection winding. The arithmetic processing part assumes a use environmental temperature of the magnetic material core from the results of the integration processing and others, and temperature dependency of magnetic characteristics of the magnetic material core.