The present invention relates to a method for preparing highly pure pancreatic progenitor cells by using pluripotent stem cells such as ES cells or iPS cells as a source, inducing their differentiation into pancreatic progenitor cells, and culturing and proliferating the pancreatic progenitor cells. Specifically, the present invention relates to a method for proliferation of pancreatic progenitor cells, comprising the step of culturing the pancreatic progenitor cells in a medium containing (i) an EGF signal transduction activator and/or an FGF signal transduction activator and (ii) a ROCK inhibitor.