Giardia intestinalis has been found in a variety of mammals, including humans, and consists of host-specific and zoonotic genotypes. There has been only 1 study of G. intestinalis infection in weasels, but the genotype of its isolate remains unclear. In this study, we report the isolation of Giardia in a ferret exhibited at a pet shop. The isolate was analyzed genetically to validate the possibility of zoonotic transmission. Giardia diagnostic fragments of the small subunit ribosomal RNA, β-giardin, and glutamate dehydrogenase genes were amplified from the ferret isolate and sequenced to reveal the phylogenetic relationships between it and other Giardia species or genotypes of G. intestinalis reported previously. The results showed that the ferret isolate represented the genetic group A-I in assemblage A, which could be a causative agent of human giardiasis.