A current sensor includes a core including groove portions and a separation wall portion, a housing covering the core and including recessed grooves formed along the groove portions, respectively, conductors positioned in the groove portions, respectively, a circuit board fixed to the housing and including a through hole and a land, the through hole penetrating in a direction corresponding to an inserting direction of the conductor, a detection element detecting a magnitude of a magnetic field and positioned in each of recessed grooves to be closer to an opening end of the groove portion relative to the conductor, the detection element being arranged so that a detecting direction of the detection element is directed along a distance direction of the groove portions, the detection element including a connection terminal positioned in the through hole, the connection terminal electrically connected to the land, and a guide portion provided at the housing.