Provided are an apparatus and a method for verifying the validity of an XML document when an XML application operates in an embedded device having a relatively low-performance processor and a small memory so as to prevent errors in the XML application due to wrong information. An XML parser using an external XML validator includes an XML receiver, an external XML validator caller, and a DOM/SAX tree generator. The external XML validator includes a schema/DTD receiver, an XML validator, and an XML validity result transmitter.