A method for manufacturing a formed product having ultra high strength and excellent durability, the method comprising: preparing heat treatable steel, the heat treatable steel consisting of, by wt%, carbon: 0.22% to 0.42%, silicon (Si): 0.05% to 0.3%, manganese (Mn): 1.0% to 1.5%, aluminum (Al): 0.01% to 0.1%, phosphorus: 0.01% or less, sulfur: 0.005% or less, molybdenum (Mo): 0.05% to 0.3%, titanium (Ti): 0.01% to 0.1%, chromium (Cr): 0.05% to 0.5%, boron: 0.0005% to 0.005%, nitrogen: 0.01% or less, optionally at least one or two selected from the group consisting of niobium (Nb): 0.01% to 0.07%, copper (Cu): 0.05% to 1.0%, and nickel (Ni): 0.05% to 1.0%, and a balance of iron (Fe) and inevitable impurities, wherein Mn and Si in the heat treatable steel satisfy Formula 1, below, and Mo/P in the heat treatable steel satisfies Formula 2, below, and wherein the forming of the heat treatable steel is performed by heating the heat treatable steel and then hot forming and cooling the heat treatable steel simultaneously, using a cooling die, wherein, in the heating of the heat treatable steel before the hot forming of the heat treatable steel, the heat treatable steel is heated to a temperature of 850°C to 950°C and maintained at the temperature for 100 seconds to 1,000 seconds, and in the cooling of the heat treatable steel after the hot forming of the heat treatable steel, the heat treatable steel is cooled to a temperature of 200°C or less at a cooling rate ranging from a critical cooling rate of martensite to 300°C/s, or wherein the forming of the heat treatable steel is performed by heating the heat treatable steel, hot forming the heat treatable steel, and cooling the heat treatable steel using a cooling medium, wherein, in the heating of the heat treatable steel before the hot forming of the heat treatable steel, the heat treatable steel is heated to a temperature of 850°C to 950°C and maintained at the temperature for 100 seconds to 1,000 seconds, and in the cooling of the heat treatable steel after the hot forming of the heat treatable steel, the heat treatable steel is cooled to a temperature of 200°C or less at a cooling rate ranging from a critical cooling rate of martensite to 300°C/s, or wherein the forming of the heat treatable steel is performed by cold forming the heat treatable steel, heating the heat treatable steel to an austenite temperature range and maintaining the heat treatable steel within the austenite temperature range, and cooling the heat treatable steel using a cooling medium, wherein the heating, maintaining, and cooling of the heat treatable steel are performed by heating the heat treatable steel to a temperature of 850°C to 950°C, maintaining the heat treatable steel at the temperature for 100 seconds to 1,000 seconds, and cooling the heat treatable steel to a temperature of 200°C or less, at a cooling rate ranging from a critical cooling rate of martensite to 300°C/s, and wherein the tempering of the formed product is performed by maintaining the formed product at a tempering temperature satisfying Formula 4, below and 250°C or less, for 15 minutes to 60 minutes, and wherein the formed product has a tempered martensite single phase microstructure or a microstructure comprising tempered martensite in an amount of 90% or greater and at least one from a group consisting of ferrite, bainite, and retained austenite as a remainder, wherein the formed product has a low-frequency fatigue life preferably within the range of 5,000 cycles or more, where the number of cycles refers to a cycle number at which fracture occurs under a strain application condition of Δε/2=±0.5% in a triangular wave form at a deformation frequency of 0.2Hz, wherein the formed product has a tensile strength of 1500 MPa or greater, and wherein the formed product has a yield ratio of 0.7 to 0.9, Mn / Si ≥ 5 Mo / P ≥ 15; forming the heat treatable steel to obtain a formed product; and tempering the formed product Tempering temperature ° C = Ttempering ° C ± 30 ° C where Ttempering (°C) = 111 ∗ -0.633, wherein in Formula 4 indicates the content of C in wt%.