a voltmeter;

a current source;

a plurality of electrodes capable of contacting a surface of an examinee and comprising a pair of a first current electrode and a second current electrode to which the current source applies current, a pair of a first voltage electrode and a second voltage electrode from which the voltmeter detects a voltage between the first voltage electrode and the second voltage electrode;

a first switch disposed between the first current electrode and the first voltage electrode;

a second switch disposed between the second current electrode and the second voltage electrode; and,

a processor configured to:

obtain a first impedance value of the examinee in a first mode in which the first switch and the second switch are in an open state;

obtain a second impedance value of the examinee in a second mode in which the first switch and the second switch are in a closed state; and

obtain bio impedance of the examinee by using the first impedance value, the second impedance value, an internal impedance value of the current source, and an input impedance value of an impedance measuring circuit as data for obtaining the bio impedance,

wherein, in the second mode, an internal impedance of the current source, an input impedance of the impedance measuring circuit, the current source and the voltmeter are parallel-connected to each other, one end of each of the internal impedance of the current source, the input impedance of the impedance measuring circuit, the current source and the voltmeter is electrically connected to both the first current electrode and the first voltage electrode in parallel, and another end of each of the internal impedance of the current source, the input impedance of the impedance measuring circuit, the electrically current source and the voltmeter is connected to both the second current electrode and the second voltage electrode in parallel.