A signal transmission device includes: a first substrate and a second substrate disposed to oppose each other in a first direction; a first resonator including a plurality of first quarter wavelength resonators provided in a first region of the first substrate, and interdigitally coupled to one another in the first direction, and a single or the plurality of second quarter wavelength resonators provided in a region of the second substrate corresponding to the first region and interdigitally coupled to one another in the first direction; and a second resonator electromagnetically coupled to the first resonator, and performing a signal transmission between the second resonator and the first resonator. The first and the second quarter wavelength resonators located at positions nearest to one another in the first resonator, respectively have open ends which are disposed to oppose one another, and respectively have short-circuit ends which are disposed to oppose one another.