A method of manufacturing an iron-copper (Fe-Cu) alloy formed by dissolving iron and copper, consisting of 82.5 to 95 atomic% of iron, 5 to 17.5 atomic% of copper and inevitable impurities, based on the total weight of the iron-copper alloy, the method comprising: a first step of preparing a ceramic melting furnace heated by high-frequency inductive heating; a second step of adding iron and copper to the ceramic melting furnace and performing dissolution and iron-copper molten metal formation; a third step of stabilizing the iron-copper molten metal by leaving the iron-copper molten undisturbed while shutting off the power supply; and a fourth step of pouring the stabilized iron-copper molten metal into a casting mold and performing casting, wherein the first step comprises performing surface treatment for forming a porous impurity absorption layer for absorbing the impurities contained in the iron-copper molten metal on an inner surface of the ceramic melting furnace, wherein zirconium silicate (ZrSiO 4) and aluminum (Al) are contained as impurity absorbents in the surface treatment, and in the second step, iron and copper are added initially in the volume ratio of 1:1 to the ceramic melting furnace to perform dissolution while stirring, and then additionally adding iron so as to have an iron-copper alloy composition consisting of 82.5 to 95 atomic% of iron, 5 to 17.5 atomic% of copper and inevitable impurities, based on the total weight of the iron-copper alloy, and the iron-copper (Fe-Cu) alloy having the following physical properties (a) to (c): (a) thermal conductivity of 70 W/m • K or higher, measured by measuring a density, specific heat and thermal diffusivity of the alloy at 25°C, and then evaluated in conformity with the ASTM E1461 standard, Laser flash: Thru-plane thermal conductivity; (b) tensile strength of 300 N/mm 2 or greater, evaluated in conformity with the KS B 0801 standard; and (c) hardness of 100 HB or greater, evaluated in conformity with the KS B 0805 standard. a first step of preparing a ceramic melting furnace heated by high-frequency inductive heating; a second step of adding iron and copper to the ceramic melting furnace and performing dissolution and iron-copper molten metal formation; a third step of stabilizing the iron-copper molten metal by leaving the iron-copper molten undisturbed while shutting off the power supply; and a fourth step of pouring the stabilized iron-copper molten metal into a casting mold and performing casting, wherein the first step comprises performing surface treatment for forming a porous impurity absorption layer for absorbing the impurities contained in the iron-copper molten metal on an inner surface of the ceramic melting furnace, wherein zirconium silicate (ZrSiO 4) and aluminum (Al) are contained as impurity absorbents in the surface treatment, and in the second step, iron and copper are added initially in the volume ratio of 1:1 to the ceramic melting furnace to perform dissolution while stirring, and then additionally adding iron so as to have an iron-copper alloy composition consisting of 82.5 to 95 atomic% of iron, 5 to 17.5 atomic% of copper and inevitable impurities, based on the total weight of the iron-copper alloy, and the iron-copper (Fe-Cu) alloy having the following physical properties (a) to (c): (a) thermal conductivity of 70 W/m • K or higher, measured by measuring a density, specific heat and thermal diffusivity of the alloy at 25°C, and then evaluated in conformity with the ASTM E1461 standard, Laser flash: Thru-plane thermal conductivity; (b) tensile strength of 300 N/mm 2 or greater, evaluated in conformity with the KS B 0801 standard; and (c) hardness of 100 HB or greater, evaluated in conformity with the KS B 0805 standard. (a) thermal conductivity of 70 W/m • K or higher, measured by measuring a density, specific heat and thermal diffusivity of the alloy at 25°C, and then evaluated in conformity with the ASTM E1461 standard, Laser flash: Thru-plane thermal conductivity; (b) tensile strength of 300 N/mm 2 or greater, evaluated in conformity with the KS B 0801 standard; and (c) hardness of 100 HB or greater, evaluated in conformity with the KS B 0805 standard.