| September 3, 2004 | Added images nos. 9 - 17 to "Teikoku Kenpo Kaiseian" in "4-9 Amendments in the House of Representatives Subcommittee, July 27 to 29, 1946". |
| November 18, 2005 | Added text-data of English documents. |
| March 6, 2006 | Achieved a liquid layout and made link to Database System for the Minutes of the Imperial Diet (Japanese only). |
| March 21, 2013 | Character code and metatag were renovated. |