At present, Japanese linguistic resources in XML format are becoming common. It is required to use these resources efficiently for Japanese linguistic studies. Therefore, we have developed a XML-tagging program Tanpopo Tagger which provides new methods for linguistic research using XML documents. This program enables linguists to mark up text strings in any XML document with original tags which have useful attributes. With this program, linguists can fully extract necessary information from the resources for their research. And also, they can save the results of the research as XML tags to reuse them in other studies. In this paper, we first describe the function and usage of this program and its usage. Next, we show some examples of study using this program, and XSLT style sheets we made for linguistic research. By applying these style sheets to the XML documents tagged by this program, linguists can easily create their original lists or tables of the strings.