The present invention provides a method of producing a sheet-like pancreatic islet, comprising culturing an isolated pancreatic islet in a culture vessel, wherein a polypeptide comprising an EC1 domain of E-cadherin and having a binding ability to said E-cadherin is fixed on or applied to a surface of a solid phase, while being adhered to the solid phase surface for a period sufficient for the pancreatic islet to take a sheet-like form.