To find out provenance of amber objects excavated from two Japanese protohistoric tombs, Nagaike tomb in Kyoto prefecture, and Todaijiyama tomb in Nara prefecture, their infrared spectra were compared with those of the geological amber specimens collected in Kuji, Choshi. Kobe (Japan), Fushun (China), New Zealand, Palmnicken (East Prussia), Dominica, and Dalmatia (Yugoslavia). Each amber shows its characteristic infrared spectrum regardless of its color. Two ambers found in protohistoric tombs in Japan were found to have the same provenance: Kuji in Iwate prefecture. Trade links between Kuji, Iwate prefecture, and two tombs in Nara and Kyoto prefectures are supposed to have been present in the protohistoric period. -- AATA