The present invention relates to a method and apparatus for authenticating various types of digital certificates by using a text embedding method. The execution of the present invention is divided into two case, one case including images in the certificate and another case not including the images in the certificate, according to the characteristics of the certificate. In the former case, a text embedding method is applied to images included in the certificate to embed a series of information text (a specific number of the certificate, and issuing organization, name of a person in charge, etc.) designated by a person who issues the certificate into the images. In the latter case, there is generated an image imperceptible to the human eve but having the same color as the ground color certificate.