We improved Raman spectroscopic densimetry for a CO2 fluid using a micro-Raman spectrometer with high spectral resolution. For precise determination of CO2 density, we obtained A, the separation of wavenumbers between two main peaks of the CO2 Raman spectrum, with a precision of +/- 0.006 cm(-1) (1 sigma). This precision will be enhanced to +/- 0.003 cm(-1) by increasing counts, corresponding to a density precision of +/- 0.0009 g cm(-3), which is approximately one order of magnitude less than that reported in earlier studies.