An individual certificate medium includes an optical security patch in which a relief layer and a metal layer include a first area and a second area. The first area includes an altered region and a portion of the relief layer overlapping with the altered region as viewed in the thickness direction of a recording layer. The second area includes a non-altered region and another portion of the relief layer overlapping with the non-altered region as viewed in the thickness direction. As viewed in the thickness direction, the first area transmits light incident thereon, while the second area absorbs light incident thereon to hide a recording region. In a direction intersecting the thickness direction, the first and second areas cause light incident on the optical security patch to emerge as diffracted light.