Mihara-ku is a ward of the city of Sakai in Osaka Prefecture, Japan. The ward has an area of 13.24 km2 and a population of 39,230. The population density is 2,960 per km2. The wards of Sakai were established when Sakai became a city designated by government ordinance on April 1, 2006. This ward includes the former town of Mihara, which joined Sakai by merger on February 1, 2005.