A current sensor includes a substrate including a through-hole and at least one groove around the through-hole, a primary conductor extending into the through-hole and through the substrate, and through which a current to be measured flows, at least one magnetic sensor that is mounted on a first surface of the substrate and detects a strength of a magnetic field generated by the current to be measured flowing through the primary conductor, and at least one magnetic body surrounding the primary conductor and including a portion extending in the at least one groove to be fixed to the substrate.