To provide a method and a device for detecting homepage falsification for promptly detecting falsification of a homepage, so that a counteractions after the falsification of the homepage can be taken promptly.

A homepage falsification detector 1 reads and copies the contents of the homepage stored in a contents storage area 5 of a WWW server 3, and stores this copy in a detecting object contents storage area 11, a falsification judging part 13 of the homepage falsification detector 1 reads both of the original contents and the copied contents with prescribed cycles from each of the contents storage area 5 and the detecting object contents storage area 11, compares both contents with each other, judges that the falsification exists when both contents do not completely coincide with each other and informs a warning device 9 of a fact.