Disclosed is an insulation circuit comprising: a first pattern formed on a first layer of a substrate, that receives high-frequency signals; a second pattern formed on this first layer next to the first pattern and that outputs the high-frequency signals received by the first pattern; a third pattern formed on a second layer different from the first layer of the substrate and connected with a signal ground, in such a way that the first and second patterns respectively overlap in plan view; and a fourth pattern formed on the second layer next to the third pattern and connected with a frame ground, in such a way that the first and second patterns respectively overlap in plan view.