Near-infrared multispectral imaging (NIR-MSI) is a potentially effective technique for quantitative evaluation of atherosclerotic plaque. NIR light shows high penetration for biological tissues and the NIR region includes the characteristic absorptions of lipid-rich vulnerable plaques, especially at wavelengths near 1200 nm. In this study, a quantitative method for assessing lipid volume fraction in plaques—one of the factors of plaque vulnerability—was developed using NIR-MSI at three wavelengths around 1200 nm. Atherosclerotic phantoms with lipid volume fractions of 100, 80, 60, 40, and 20 vol% were prepared and measured by NIR-MSI at three wavelengths: 1150, 1200, and 1300 nm. The acquired datasets were processed by the spectral angle mapper method. Consequently, lipid-enhanced multispectral images of the phantoms were created. In addition, the differences in lipid volume fraction were evaluated and the fractions were classified into six grades quantitatively. These results show the potential of NIR-MSI for the quantitative evaluation of vulnerable plaques.