Kim, Y.S, Cha, Y.H., Shin, C.S., Ko, S.W. and Seo, Y.T., 2009. Improved logarithmic waveform inversion considering the power-spectrum of the wavefield. Journal of Seismic Exploration, 18: 215- 228. Local minima of an objective function in waveform inversion often prevent solutions from converging to the global minimum in cases where an initial velocity model for the inversion is far from the true velocity structure. In particular, forward-modeled wavefields with small power-spectrum values in the logarithmic objective function cause the numerical instability in the calculation of the gradient direction. Hence, it is important to remove these small values to allow a solution of the logarithmic objective function to converge to the global minimum. To mitigate the instability, we developed a frequency-domain waveform inversion algorithm taking into consideration the power-spectrum of the wavefield in the process of the calculation of the logarithmic objective function. By calculating the objective function using only wavefields with relatively large values of the power-spectrum, we confirmed that the number of local minima was reduced and the shape of the misfit function was suitable for the gradient-type inversion. We demonstrated our technique for waveform inversion through two numerical examples of the 2D profiles of SEG/EAGE salt and overthrust models.