The present invention relates to multipotent adult stem cells derived from canine umbilical cord blood, placental blood and blood sample from canine fetal heart, and a method for preparing the same as well as a cellular therapeutic agent containing the same, more specifically, to a multipotent adult stem cell isolated by culturing an eukaryotic cell derived from canine umbilical cord blood, placental blood and blood sample from canine fetal heart in a FBS-containing medium and a method for preparing the same. Adult stem cells according to the present invention are derived from canine umbilical cord blood, placental blood and blood sample from canine fetal heart. The adult stem cells have characteristics highly similar to human mesenchymal stem cells as well as remarkable cell growth at the initial step compared to human UCB-derived mesenchymal stem cells so that the cells are useful to treat canine incurable diseases and difficult-to-cure diseases. Furthermore, multipotent adult stem cells are effective to treat musculoskeletal diseases and neural diseases due to the ability to differentiate into osteogenic cells and neural cells.