The solar reflective performance of several retroreflective materials are evaluated by outdoor measurements. Their reflectances were derived from the quantity of heat energy received, which were calculated from temperature data. By correcting the measured data to fit the reflectivities of several non-retroreflective materials, the value of retroreflective component can be determined with an accuracy of about 1 percent, irrespective of measurement date. The measured retroreflective components are 5 and 13 percent for the bead-embedded type, 18 percent for the capsule-lens type, and 24 and 30 percent for the prism-array type.