Korean field mouse (Apodemus peninsulae) are widely distributed throughout Northeastern Asia comprisingmany regions in many countries, including Russia, Japan, Korean Peninsulae, Mongolia and China. We analyzed mitochrondrial cytochrome b gene (1143 bp) of the Apodemus peninsulae and 11 specimens were collected from Bogd Khan Strictly Protected Area in Mongolia. We identified two different haplotypes from five new sequences. The genetic distance for Mongolian first haplotype was 0-1.8% while second haplotype depicts relatively high genetic distance (1.1-2.6%). This molecular genetic analysis demonstrates that A.peninsulae from the populations in regions of Russia such as Zabaikal, Khabarovsk, and Sakhalin are close to population in Mongolia in terms of the first haplotype. However the second haplotype from Mongolia is similar with the populations of Korea and China and form clade with strong maximium likelihood (86%) bootstrap support. As a result, we assume that there might be two different subspecies in Bogd Khan Strictly Protected Area of Mongolia.