Lacquer-like films on the surfaces of potsherds excavated from Korekawa remains and Ayukawa cave in the Hokkaido Pref. of the Jomon period (earlier than 3rd century B.C.) were analyzed by means of infrared absorption spectroscopy. The samples were treated with carbon tetrachloride to separate soluble organic matters, and then soluble parts and insoluble parts were subjected to infrared spectroscopy. The potsherds excavated from Korekawa remains were found to be coated with Urushi, asphalt and red iron oxide. From the fact that coated films containing red iron oxide had fresh and bright color, it is supposed that the process of Kurome might have already been carried out at the late Jomon period. It was also found that asphalt had been used as an adhesive for keeping chalcedony beads inserted in earthen dolls.