In a magnetic coupler device comprising: a magnetic field generation circuit generating a magnetic field according to an input current; and a detection bridge circuit including a pair of magnetoresistance effect devices, a resistance value of each of the magnetoresistance effect devices changing by applying a magnetic field generated by said magnetic field generation circuit to each of the magnetoresistance effect devices, and having two outputs between which a voltage difference is generated according to an intensity of the magnetic field generated by said magnetic field generation circuit, by forming a geometric shape of each of said magnetic field generation circuit and said detection bridge circuit in line symmetric or point symmetric, a high S/N ratio is obtained even with high frequency.