Onoda (小野田市; -shi) was a city located in Yamaguchi Prefecture, Japan. The city was founded on November 3, 1940.
As of 2003, the city had an estimated population of 44,953 and the density of 1,044.20 persons per km². The total area was 43.05 km².
On March 22, 2005, Onoda was merged with the town of San'yō, from Asa District, to form the new city of San'yō-Onoda.