The use of internet has been increasing rapidly. The number of published web pages increase as well. On the other hand, web pages have tags and syntaxes inside. Those tags and syntaxes are going to be rendered into an interface by a web browser. The web page needs to be correctly setup structurally and grammatically before it is published. A web page can be claimed correct of valid after it is checked by a validation system. A validation system contains 3 main processes, lexical analysis, parsing, and token checking proceses. Those which are going to be checked are element name, attribute name, and atribute content based on the DTD's standard. Checking process inclues the checking of structure of a web page. This validation system can help the web developer in creating a correct web page. This validation system can detect an error inside an XHTML file, including grammatical error and structual error. Keywords: XHTML, DTD, Lexical Analysis, Parsing, Checking, Token