The present invention provides: a method for producing mixed cells comprising cardiomyocytes, endothelial cells and mural cells from induced pluripotent stem cells, the method comprising (a) a step of producing cardiomyocytes from induced pluripotent stem cells and (b) a step of culturing the cardiomyocytes in the presence of VEGF; and a therapeutic agent for heart diseases, comprising the mixed cells produced by the method.