An object of the present invention is to provide a stem cell applicable to regenerative therapeutic method, and to provide a technique to carry out regenerative therapy using the cell. A collected cardiac tissue fragment is enzymatically treated to prepare a cell suspension. Then using the cell suspension, following steps are carried out: (1) separation of cells by the density gradient method, (2) suspension-culture in a culture medium containing fibroblast growth factor and epidermal growth factor and (3) selection and separation of cells forming a floating sphere to obtain pluripotent stem cells. Thus-obtained pluripotent stem cells are used to carry out regenerative therapy.
