This study reports radiocarbon dates of more than 30 samples of charred residues on pottery sherds of the Incipient Jomon period. The ages of Linear-relief (Ryukisenmon) pottery were 15,300–13,700 cal BP, with great differences among the samples. The pitted decoration (Enkomon), Nail-impressed (Tsumegatamon), and pressing and dragging (Oshibikimon) types date to 13,800–12,400 cal BP. For pottery of the same type, differences among sites were large. At the Unokiminami site, the impressed cord mark (Oatsu Jomon) is the main pottery type, including Nail-impressed. The latter shows a slightly older age. Stable isotope and elemental analyses were used to ascertain the origin of charred residues on the pottery. In the data set of Jomon pottery of the oldest type, residues consisting only of cooked nuts were found. However, Jomon people, even from early times, are thought to have cooked mixed plant and animal ingredients, including marine products.