A technique based on micro reflectance spectroscopy using a vacuum Furier Transform infrared (FT-IR) spectrometer has developed for the quantitative measurement of dissolved water in melt inclusions in phenocrysts. The technique is superior in sample preparation to the conventional transmission method, which requires doubly polished samples with known thickness. Four synthesized glass samples with H₂O contents ranging 1.17 to 4.05wt% were examined in this study. A linear correlation between the logarithm of reflectance intensities around 3650cm^-1by H-bearing species and the water content of the glasses is obtained. At the lateral resolution of 30μm, the precision of the measurement caused by random error is 0.23wt% (1σ), and the value is low enough to apply the technique to the measurement of dissolved water in melt inclusions. A method which corrects possible contamination of inclusion spectra by the olivine host is also proposed.