石冈市（日语：石冈市／いしおかし）是位于关东北部、茨城县南部的一市。是常陆国的国府所在地。

Ishioka(石岡市,Ishioka-shi) is a city located in Ibaraki Prefecture, in the northern Kantō region of Japan. As of September 2015, the city had an estimated population of 75,906 and a population density of 352 persons per km². Its total area was 215.53 square kilometres (83.22 sq mi).