Koishikawa (小石川) is a district of Bunkyo, Tokyo. It consists of five sub-areas, 1-5 chome (1~5丁目). It is located nearby with the same name are two well regarded gardens: the Koishikawa Botanical Garden (related to Tokyo University) in Hakusan, and the Koishikawa Korakuen Garden in Korakuen.
The Koishikawa arsenal was an important military installation during the Meiji era.
Bunkyo operates the local public elementary and middle schools.