| 1976 | Completed the storage of cultural assets (managed by the Social Education Division)
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| 1979 | Established Tokamachi City Museum Frinds
Tokamachi City Museum opened (independent from Social Education Division)
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| 1986 | Opening of the Botanical Garden
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| 1988 | Opening of the “Iseki Hiroba”(Historical Site Park)
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| 1989 | Completion of Chijimi storage and museum extension
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| 1990 | Established Cultural Property Division
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| 1991 | Opening of the Archeology exhibition room
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| 1994 | Completed replacement of permanent exhibition
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| 1988 | Completion of expansion of a special exhibition room for object unearthed at the Sasayama Site
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| 2004 | Chuetsu Earthquake
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| 2007 | Chuetsu-oki Earthquake
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| 2009 | Reconstruction of the renovated residence of the “Iseki Hiroba”
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| 2012 | Nagano Prefecture Northern Earthquake
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| 2014 | Completion of repair of thatched roof of a restored house in the “Iseki Hiroba”(Historical Site Park)
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| 2019 | Closed from December 2nd
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