We investigated mitochondrial DNA haplogroups of four Jomon individuals from the Sanganji shell mound in Fukushima, Tohoku district, Japan. Partial nucleotide sequences of the coding and control region of mitochondrial DNA were determined. The success rate of sequencing increased when we analyzed short DNA sequences. We identified haplogroups from all four samples that were analyzed; haplogroup frequencies were 50% (n = 2) for N9b and 50% (n = 2) for M7a2. Haplogroup N9b has been previously observed in high frequencies in the other Tohoku Jomon, Hokkaido Jomon, Okhotsk, and Ainu peoples, whereas its frequency was reported to be low in the Kanto Jomon and the modern mainland Japanese. Sub-haplogroup M7a2 has previously been reported in the Hokkaido Jomon, Okhotsk, and modern Udegey (southern Siberia) peoples, but not in the Kanto Jomon, Ainu, or Ryukyuan peoples. Principal component analysis and phylogenetic network analysis revealed that, based on haplogroup frequencies, the Tohoku Jomon was genetically closer to the Hokkaido Jomon and Udegey people, than to the Kanto Jomon or mainland modern Japanese. The available evidence suggests genetic differences between the Tohoku and Kanto regions in the Jomon period, and greater genetic similarity between the Tohoku Jomon and the other investigated ancient (Hokkaido Jomon, Okhotsk) and modern (Siberian, Udegey in particular) populations. At the same time, the Tohoku and Hokkaido Jomon seem to differ in sub-haplotype representations, suggesting complexity in Jomon population structure and history.