To store a structured document suitable for retrieval at a high speed and the improvement of the using efficiency of memory resources regarding a structured document storage device.

This structured document storage device is provided with a document decomposition processing part 21 for decomposing the original text 1 of the structured document into a tree structure composed of nodes and elements, a structure constitution processing part 22 for constituting a tag list structure based on the result of decomposition and a structure storage part 3 for storing at least the tag list structure. The tag list structure is composed of a tag number array 31 and a tag list 32. The tag number array 31 stores tag numbers uniquely determined for the respective kinds of tags which are information for indicating the kinds of the elements for the tags of the elements included in the original text 1 of the structured document and pointers to the tag list 32 corresponding to them. The tag list 32 is composed by connecting the nodes provided with the tags of the same kind or the tags of the different kinds in mutually same relation.