To identify subspecies of the sika deer, Cervus nippon, and to select C. n. hortulorum individuals for restoration of this subspecies in Korea, we obtained cytochrome b partial sequences (375 bp) of sika deer (C. nippon) from deer farms in northeastern China, North Korea, mainland Korea, and Jeju Island. Based on noninvasive samples, these cytochrome b sequences were compared with the corresponding haplotypes of sika deer, which were obtained from GenBank. We identified five individuals of sika deer from deer farms in northeastern China and North Korea as C. n. hortulorum, and found that interbreeding between individuals belonging to different subspecies is common on deer farms in far-eastern Asia. We concluded that the five C. n. hortulorum individuals on deer farms from northeastern China and North Korea, detected in this study, cannot be considered as pure descendants of C. n. hortulorum in the wild.