Ōigawa (大井川町, Ōigawa-chō) was a town located in Shida District, Shizuoka Prefecture, Japan. As of 2008, the town had an estimated population of 22,695 and a density of 962.92 persons per km². The total area was 24.54 km². On November 1, 2008, Ōigawa was merged into the expanded city of Yaizu and thus no longer exists as an independent municipality.