The Miyagase Dam is a dam on the Nakatsu River, a main tributary of the Sagami River in Aikō District, Kanagawa Prefecture, Japan. It straddles the border between the village of Kiyokawa, town of Aikawa and the former town of Tsukui (now part of the city of Sagamihara).
The potential of the Sagami River for hydroelectric power development began to be developed in the 1930s, with the growth of industry and electrical consumption in the Yokohama-Kanagawa industrial belt. Work on the Sagami Dam, the first dam on the main stream of the Sagami River began in 1938; however, lack of funding and the advent of World War II delayed completion until after the end of the war. Work on the Shiroyama Dam was completed in 1965. The growth in population of nearby Atsugi and increased need for industrial and drinking water spurred plans for additional dams on the Sagami River's tributaries. Plans for the Miyagase Dam were finalized in 1969 with work commencing in 1971. Due to the huge