Abstract: An electric current sensor includes an upper shield case, a lower shield case, a press-fit member and an inner member. The upper shield case has at least an upper surface and an upper outer peripheral portion. The upper outer peripheral portion extends downward in an up-down direction from an outer edge of the upper surface. The lower shield case has at least a lower surface and a lower outer peripheral portion. The lower outer peripheral portion extends upward in the up-down direction from an outer edge of the lower surface. The upper shield case and the lower shield case form an accommodating portion. The press-fit member has a main portion. The main portion pushes both of the upper outer peripheral portion and the lower outer peripheral portion outward in a horizontal plane perpendicular to the up-down direction to integrally fix the upper and lower shield cases to each other.