Provided are a ferritic/martensitic oxide dispersion strengthened steel with increased high temperature creep resistance, including 0.02 to 0.2 wt % of carbon (C), 8 to 12 wt % of chromium (Cr), 0.1 to 0.5 wt % of yttria (Y2O3), 0.2 to 2 wt % of molybdenum (Mo), 0.01 to 0.5 wt % of titanium (Ti), 0.01 to 1 wt % of manganese (Mn), 0.01 to 0.3 wt % of vanadium (V), 0 to 0.3 wt % of zirconium (Zr), 0 to 0.5 wt % of nickel (Ni), and the remaining content of iron (Fe), and a method of manufacturing the same. The ferritic/martensitic oxide dispersion strengthened steel may be useful as a material for core structural components of a nuclear power system, ultra supercritical pressure steam generator components of a thermal power plant, or engine components of an airplane due to a high tensile strength at 700° C. and excellent creep resistance.