Cells in vivo are surrounded by extracellular matrices (ECMs). Polyelectrolyte complex (PEC), compose of polysaccharides, has a similar structure as ECMs. We have already reported that polysaccharide type PEC could control some cell functions. In this study, We will discuss the differentiation of embryonic stem (ES) cell by using synthetic PEC as culture materials. On the synthetic type PEC, ES cell differentiated to various type of tissue cells than that on the tissue culture dish. On the sulfonic type PEC, neuron like cells with long neurite were observed. On the other hand, intestine like structures with peristalsis was observed on carboxy type PEC. As a result it was suggested that functional group of PEC effect the differentiation of ES cells.