The chromosome number of myoga ginger (Zingiber mioga (Thunb.) Roscoe: Zingiberaceae) has been reported as 2n = 22 for Chinese plants and 2n = 55 for Japanese plants. We checked the chromosome number of Z. mioga in plants collected in Jeollabuk-do and Jeollanam-do, Korea, and counted 2n = 44, the first report of this number for the species. As the basic chromosome number of Z. mioga is thought to be x = 11, Z. mioga plants in China, Korea, and Japan appear to be diploids, tetraploids, and pentaploids, respectively. In finding the tetraploid race of Z. mioga in Korea, we can hypothesize that the pentaploid race in Japan is derived through the fertilization of reduced gametes of the diploid race and unreduced gametes of the tetraploid race.