Numazu (沼津市, Numazu-shi^?) is a city located in eastern Shizuoka Prefecture, Japan. As of 2009, the city has an estimated population of 205,636 and a population density of 1,100 persons per km². The total area was 187.11 km².

Numazu is at the northern end of the Izu Peninsula, which is a leisure destination known for its numerous hot springs. Mount Fuji, Japan's tallest mountain, may also be seen from Numazu on clear days. Numazu is located 130 kilometres (81 mi) west of Tokyo and is on the Tōkaidō Main Line, the main railway line from Osaka to Tokyo. Warmed by the Kuroshio Current, the area enjoys a warm maritime climate with hot, humid summers and mild, cool winters. The Kano River runs through the middle of the city.

Numazu is an ancient settlement, mentioned in Nara period records as the original provincial capital of Suruga Province before the separation of Izu Province from Suruga in 680, and subsequent transfer of the provincial capital to the banks of the Abe River in what is now Shizuoka city. During the early part of the Tokugawa shogunate, Numazu was ruled as part of Odawara Domain, but with the construction of Numazu Castle in 1777, it became the separate Numazu Domain. Numazu prospered in the Edo period from its location on the Tōkaidō, with Numazu-juku and Hara-juku as two of the 53 post stations.