You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allredirects arcontinue="ver4/関数リファレンス/BcBaser_content" />
  </query-continue>
  <query>
    <allredirects>
      <r ns="0" title="baserCMS 利用ガイド" />
      <r ns="0" title="baserCMS 開発ガイド" />
      <r ns="0" title="baserCMS公式ガイドとは" />
      <r ns="0" title="ver4/関数リファレンス/BcBaser addCrumb" />
      <r ns="0" title="ver4/関数リファレンス/BcBaser baseUrl" />
      <r ns="0" title="ver4/関数リファレンス/BcBaser blogPosts" />
      <r ns="0" title="ver4/関数リファレンス/BcBaser cacheHeader" />
      <r ns="0" title="ver4/関数リファレンス/BcBaser changePrefixToAlias" />
      <r ns="0" title="ver4/関数リファレンス/BcBaser charset" />
      <r ns="0" title="ver4/関数リファレンス/BcBaser checkUpdate" />
    </allredirects>
  </query>
</api>