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Fraction of vegetation cover (FVC) has been used for environmental studies of both regional and global scale, and data products of similar kinds have been generated from several agencies. Although there are differences in sensors/datasets used and algorithms employed among those products, many of those use spectral mixture analysis either directly or indirectly, and/or assume an essence of spectral mixture in their models. In the FVC estimations, noises in reflectance spectra of both target and endmember are propagated into the estimated FVC. Those propagation mechanisms such as patterns and degree of influences need to be clarified analytically, where this study tries to contribute. The objective of this study is to investigate characteristics of the noise propagation into the estimated FVC based on one of the linear mixture models known as VI-isoline based LMM. In order to facilitate analytical discussions, the number of endmember spectra is limited into two. In addition, a band-correlated noise is assumed in both reflectance spectrum of a target pixel and endmember spectra of vegetation and non-vegetation surfaces. The propagated error in FVC from those spectra is analytically derived. The derived expressions indicated that the characteristic behavior of the propagated errors exists such that there are certain conditions among the band correlated noises which result in the cancellations of propagated errors on FVC value (it looks as if the spectra are noise-free). Findings of this study would reveal unknown behavior of the propagated noise, and would contribute better understanding of FVC retrieval algorithms of this kind.