Time                     Twin city                                            Friendly-exchange-relations city

Apr. 1983             Nagaokakyo (Japan)                          

Oct. 1986             Aachen (Germen)                              

May 1988             Wilmingto USA                                 

Mar. 1990             Rouen (France)                                  

Oct. 1991                                                                        Masuda (Japan)

Feb. 1995                                                                        Ueda (Japan)

Oct. 1995                                                                        Barcelona (Spain)

Jun. 1997                                                                         Sunchon (the Republic of Korea)

Nov. 1998            Waitakere (New Zealand)                  

May 1999                                                                        Surrey (Canada)

Sep. 2000                                                                        Houston (USA)

Jan. 2002              Santos (Brazil)                                   

Sep. 2002                                                                        Wiener Newstadt (Austria)

Sep. 2002                                                                        Daegu (the Republic of Korea)

Jul.2003                Veszprem (Hungary)                          

Sep. 2003              Nelson Mandela  (South Africa)        

Jun.2004               Varna (Bulgaria)                                 

Sep. 2004              Stavanger (Norway)                           

Sep. 2005              Nottingham(UK)                                      Verona(Italy)

Oct. 2005   Bydgoszcz(Poland)