A method of producing a coal blend by blending plural brands of coal to produce a coal blend includes letting a surface tension of coal when inert material is assumed to be 100 vol % be γ100, and letting a surface tension of coal when reactive material is assumed to be 100 vol % be γ0, determining γ0 of coal; among brands of coal 1, 2, . . . i, . . . , and n to be blended in a coal blend, specifying coal i in which γ100 is outside of γ0; measuring TI of coal i; and determining a blending ratio of coal i such that w calculated by formula (1) is 20.4 mass % or less w=Σ(xi×TIi)  (1).