An aspect of the present disclosure, there is provided a magnetic detection device including a magnetic detection unit including a magnetic sensor unit and a comparison unit, the magnetic sensor unit detecting a magnetic flux density, amplifying the detection signal and outputting an output signal to the comparison unit as a mode selected from one of a first mode and a second mode of which power consumption is lower than that of the first mode, the comparison unit comparing the output signal and a reference voltage as a threshold level which determines magnetic field being formed or not, and outputting a comparison result, a conversion gain control unit outputting a mode signal based on the comparison result to the magnetic sensor unit as the second mode when the mode signal is larger than the threshold level or as the first mode when the mode signal is smaller than the threshold level so as to control the magnetic sensor unit.