A method of producing a liquid fuel comprising the steps of: hydrotreating a feed oil containing paraffinic hydrocarbons each having 20 to 100 carbon atoms as main components in the presence of hydrotreating catalyst at a temperature of 200 to 350 °C, at the liquid hourly space velocity of 0.1 to 5.0 h -1, and under the partial pressure of hydrogen in the range from 0.5 to 8 MPa to obtain an effluent oil, said feed oil being FT wax produced by the Fischer-Tropsch synthesis; and fractionating the effluent oil to obtain middle distillate including a gas oil with a cetane number of 75 or more and with a pour point of -27.5 °C or lower at a yield of the middle distillate oil of 55% or more with respect to the total weight of the feed oil, wherein the hydrotreating catalyst includes an active metal component comprising platinum or palladium supported on a carrier containing an amorphous solid acid and a ultra-stable Y-type zeolite with an average particle diameter of 0.2 to 1.0 μm, a crystallinity of 1.02 to 1.10 based on the standard Y-type zeolite basis, and a specific surface area of 700 to 790 m 2 /g, wherein the amorphous solid acid includes one or more selected from the group consisting of amorphous silica alumina, said amorphous silica alumina containing SiO 2, as a component, by 50 to 95 mass %, amorphous silica zirconia, said amorphous silica zirconia containing SiO 2, as a component, by 10 to 50 mass %, and amorphous alumina boria, said amorphous alumina boria containing Al 2 O 3, as a component, by 10 to 30 mass %, and also the hydrotreating catalyst has functions of dehydrogenating, isomerizing, hydrocracking, and hydrogenating hydrocarbons, and whereby the crystallinity of the USY zeolite is calculated against that of the standard Y-type zeolite which is SK-40 produced by Union Carbide Corp as a reference material and whereby a total peak height H for the 331 plane, 511 plane, 440 plane, 533 plane, 642 plane and 555 plane for X-ray diffraction of the USY zeolite and the total peak height Ho for the same planes of SK-40 are measured and the crystallinity is calculated through the following expression, assuming that a crystallinity of the SK-40 is 1: Crystallinity = H/ Ho. hydrotreating a feed oil containing paraffinic hydrocarbons each having 20 to 100 carbon atoms as main components in the presence of hydrotreating catalyst at a temperature of 200 to 350 °C, at the liquid hourly space velocity of 0.1 to 5.0 h -1, and under the partial pressure of hydrogen in the range from 0.5 to 8 MPa to obtain an effluent oil, said feed oil being FT wax produced by the Fischer-Tropsch synthesis; and fractionating the effluent oil to obtain middle distillate including a gas oil with a cetane number of 75 or more and with a pour point of -27.5 °C or lower at a yield of the middle distillate oil of 55% or more with respect to the total weight of the feed oil, wherein the hydrotreating catalyst includes an active metal component comprising platinum or palladium supported on a carrier containing an amorphous solid acid and a ultra-stable Y-type zeolite with an average particle diameter of 0.2 to 1.0 μm, a crystallinity of 1.02 to 1.10 based on the standard Y-type zeolite basis, and a specific surface area of 700 to 790 m 2 /g,