Matsumoto (mätsŏmōˈtō) [key], city (1990 pop. 200,715), Nagano prefecture, central Honshu, Japan. It is a market for silkworms and raw silk. Industries include computer components, food processing, machine-building, and textile manufacturing. The 17th-century Matsumoto castle is the oldest surviving castle in Japan. There are museums of folklore, folkcraft, and ukiyo-e prints.