A cap seal includes a cylindrical member covering a side face of the container, and a top face including an IC tag and connected to a first end that is one of two axial ends of the cylindrical member to close the cylindrical member at the first end. The cylindrical member includes a metal portion disposed on the side face of the container, and at least one insulating portion extending from the first end. The cylindrical member forms a closed annular shape in a circumferential direction of the cylindrical member, and the metal portion and the insulating portion are joined to each other.