The present invention relates to a method for producing an insulin-producing cell population or a pancreatic β cell population with reduced Ki67-positive cells, comprising treating a population of endocrine precursor cells or cells in a subsequent differentiation stage with an FGFR1 inhibitor.本發明係有關一種Ki67陽性細胞經減低之胰島素產生細胞團或胰島β細胞團之製造方法,該製造方法係包含將內分泌前驅細胞或處於之後的分化階段之細胞團以FGFR1抑制劑處理。