To provide an ID card whereby even when the ID card is tampered by fraudulently substituting a photo image, the tampering is easily detected.

Assuming that a watermark image including ID information is an image existing in a frequency region, inverse conversion from a frequency region is applied to the entire image of the watermark image to obtain a converted image. The converted image is added to the photo image to obtain an embedded image wherein the ID information is embedded as an electronic watermark. The embedded image is recorded on a prescribed card by printing to produce the ID card.