We have successfully developed a simple, laboratory-sized EUV reflectometer EUMOR (extreme Ultraviolet Monochromatic Reflectometer). A CO2 gas-jet-target laser-plasma source was employed as the EUV source for EUMOR. EUMOR uses a single line emission at the wavelength of 12.98 nm from a CO2 gas-jet-target laser-plasma source without a grating, therefore it can achieve simultaneous high spectral resolution and high throughput. The intensity of EUV emission from the CO2 gas-jet target laser-plasma was quantitatively evaluated, and the EUV flux that irradiated the surface of a sample was estimated to be 5x10(superscript 5 photons/shot. Four Mo/Si multilayer mirrors which were deposited under the same conditions with different layer periods were measured by EUMOR. The parameters of these multilayer mirrors, which were obtained by parameter fitting to the measured angular distribution of the reflectivity, showed good agreement with each other, demonstrating the reliability of EUMOR data.