Invasive species often spread distribution rapidly. This seems to be discrepant to the fact that the distribution of many species is limited by environmental conditions. Even in a species that is distributed over a wide range, there are genetic differentiations among populations along environmental gradients, suggesting that the environmental range of one genotype is limited and large distribution is possible by genetic differentiations. Then, what are the mechanisms that enable the rapid spreading of invasive species? We address three hypotheses. (1) A genotype of invasive species has an adaptability to wide range of environmental conditions. (2) Multiple genotypes that have pre-adapted to different environmental conditions have invaded into different habitats. (3) New genotypes adapted to new environments evolve after invasion. In this study, we studied the population genetic structure of an invasive plant Cardamine hirsuta in eastern Japan, where there is a large temperature gradient along the latitude. C. hirsuta is an invasive plant native to Europe that invaded Japan in the 1970s and can now be found all over Japan. Our results showed there are four lineages and four populations in eastern Japan. Two populations were widely distributed in eastern Japan, which is consistent with the hypothesis 1. The other two populations were distributed in relatively narrow areas; one of them was found in the northern areas while the other was found in the southern area in eastern Japan, which is consistent with the hypothesis 2. One of the populations was identified as a mixture of two populations and suggested to appear after the first discovery in Japan, which is consistent with the hypothesis 3. Our results suggest that the invasion patterns differ among populations, which may help their rapid spreading to the new environment.