A stress measurement method for an object to be measured that includes a substrate and a coating film, the stress measurement method comprising: vibrating the object to be measured at a plurality of oscillation frequencies; measuring a temperature amplitude of the object to be measured by using a temperature sensor; identifying (S16, S36) parameters of a one-dimensional heat conduction equation described below by performing curve-fitting, based on the one-dimensional heat conduction equation, on a measurement value of the temperature amplitude with respect to frequency characteristics of a temperature change component and a phase component based on a thermoelastic effect, the frequency characteristics being obtained at the plurality of oscillation frequencies, the one-dimensional heat conduction equation indicating a theoretical solution of a temperature amplitude on a surface of the coating film based on heat conduction and the thermoelastic effect of each of the substrate and the coating film, T theory ∗ = T ∧ theory T 0 = − C 4 1 − C 1 sinh 1 + i ω ∗ 2 C 2 C 3 tanh 1 + i ω ∗ 2 + 1 tanh 1 + i ω ∗ 2 C 2 + C 1 C 1 = c 1 c 4 c 3 = E c 1 − v c E m 1 − v m ⋅ α c α m ⋅ ρ m c m ρ c c c = E c 1 − v c E m 1 − v m ⋅ K c K m C 2 = c 3 c 5 2 c 2 = L c L m 2 k c k m ⋅ ρ m c m ρ c c c = L c L m 2 α c α m C 3 = c 2 c 3 = ρ c c c k c ρ m c m k m = b c b m C 4 = c 6 T 0 = εK m σ m where T 0 is reference temperature, T^ theory is Fourier transform of temperature, E is a modulus of longitudinal elasticity, K is a thermoelastic constant, v is a Poisson's ratio, c is specific heat at constant pressure, k is heat conductivity, ρ is density, α is a linear expansion coefficient, L is film thickness, σ is principal stress sum, and a subscript m and a subscript c respectively indicate the substrate and the coating film; wherein the parameters of one-dimensional heat conduction equation composes only C 1, C 2, C 3, and C 4; and obtaining (S17, S37) a stress of the object to be measured based on the parameters that have been identified. vibrating the object to be measured at a plurality of oscillation frequencies; measuring a temperature amplitude of the object to be measured by using a temperature sensor; identifying (S16, S36) parameters of a one-dimensional heat conduction equation described below by performing curve-fitting, based on the one-dimensional heat conduction equation, on a measurement value of the temperature amplitude with respect to frequency characteristics of a temperature change component and a phase component based on a thermoelastic effect, the frequency characteristics being obtained at the plurality of oscillation frequencies, the one-dimensional heat conduction equation indicating a theoretical solution of a temperature amplitude on a surface of the coating film based on heat conduction and the thermoelastic effect of each of the substrate and the coating film, T theory ∗ = T ∧ theory T 0 = − C 4 1 − C 1 sinh 1 + i ω ∗ 2 C 2 C 3 tanh 1 + i ω ∗ 2 + 1 tanh 1 + i ω ∗ 2 C 2 + C 1 C 1 = c 1 c 4 c 3 = E c 1 − v c E m 1 − v m ⋅ α c α m ⋅ ρ m c m ρ c c c = E c 1 − v c E m 1 − v m ⋅ K c K m C 2 = c 3 c 5 2 c 2 = L c L m 2 k c k m ⋅ ρ m c m ρ c c c = L c L m 2 α c α m C 3 = c 2 c 3 = ρ c c c k c ρ m c m k m = b c b m C 4 = c 6 T 0 = εK m σ m where T 0 is reference temperature, T^ theory is Fourier transform of temperature, E is a modulus of longitudinal elasticity, K is a thermoelastic constant, v is a Poisson's ratio, c is specific heat at constant pressure, k is heat conductivity, ρ is density, α is a linear expansion coefficient, L is film thickness, σ is principal stress sum, and a subscript m and a subscript c respectively indicate the substrate and the coating film; wherein the parameters of one-dimensional heat conduction equation composes only C 1, C 2, C 3, and C 4; and obtaining (S17, S37) a stress of the object to be measured based on the parameters that have been identified.