Abstract: An interference type optical magnetic field sensor device 1 has a light emitter 10 emitting first linearly polarized light, a first optical element 30 emitting a first linearly polarized wave and a second linearly polarized wave orthogonal to the first linearly polarized wave with respect to incident the first linearly polarized light, and emitting a second linearly polarized light with respect to incident third linearly polarized wave and a forth linearly polarized wave orthogonal to the third linearly polarized wave, a magnetic field sensor element 50 disposed at least a portion thereof within a predetermined magnetic field an optical path unit 40 connected to the first optical element and the magnetic field sensor element, and having a first optical path propagating the first linearly polarized wave and the forth linearly polarized wave, and a second optical path propagating the second linearly polarized wave and the third linearly polarized wave, a detection signal generator 60 outputting a detection sign