The Hagi Museum, located in the Horiuchi Preservation District for Groups of Traditional Buildings is a core facility for the city-wide Open Air Museum municipal tourist project.
This museum was opened in 2004 on the theme of Hagi and has collections of documents and materials in the fields of natural sciences, history, folklore, industry, fine arts and craftwork. Some of these are on display for the public. Among these collections are letters, helmet and shamisen of Takasugi Shinsaku, a local military and political leader of Hagi who worked against the Tokugawa Shogunate in the 19th century. These articles testify to his “condensed” life.

This museum itself is a fine building with an oxidized silver-colored tiled roof and facades of namako kabe (lozenges of black, flat tiles with protruding joints of white plaster), a feature of the Preservation District for Groups of Traditional Buildings.

The Hagi Museum holds a number of exhibitions throughout the year. Themes range from history to nature and folklore, and special exhibits of valuable artifacts are included.

The museum gift shop inside the building offers a wide variety of unique merchandise related to the Hagi Museum. The restaurant also offers unique dishes made using ingredients from Hagi and Yamaguchi Prefecture, including the popular summer orange soft ice cream.