Abstract: According to an embodiment, there is provided a security method of XML web document, and in particular, a method of encrypting a tag set by a user when generating an XML document to display data contents of the encrypted tag as a web document. The security method of XML web document includes setting, by the processor, an encryption tag to be encrypted according to setting of a user; generating, by the processor, an XML document including the encryption tag based on data input by the user; retrieving, by the processor, the set encryption tag of the XML document; and generating, by the processor, an encrypted text for data corresponding to the encryption tag and outputting the encrypted text on a View window, and a plain tag format and the encryption tag format are maintained as they are and displayed on the View window, and only the data corresponding to the encryption tag is displayed on the View window as the generated encrypted text.