Since a luminosity upgrade of the LHC is scheduled, an upgrade of the CMS experiment is also planned. As part, detectors based on the gas electron multiplier (GEM) technology will be installed in the CMS endcaps. The Korean CMS group is one the group responsible for the large GEM foil production. As the foils are produced by a new manufacturer, Mecaro, an extensive quality check was planned and implemented. Several CMS GE1/1 GEM detectors with GEM foils produced by Mecaro have been assembled and the properties of those detectors have been measured. According to the measurements, the Mecaro foils are as good as CERN foils in terms of the effective gas gain, the uniformity of the gain, the rate capability and the radiation hardness. The results of the validation are presented.