FIELD : chemistry.SUBSTANCE : invention relates to the field of biotechnology, in particular to the means to maintain or stimulate, cosmetic product, pharmaceutical product, therapeutic and prophylactic drug, a food product and an undifferentiated state of embryonic stem cells or somatic stem cells, a wound treatment agent, and a method for growing embryonic stem cells, excluding human embryonic stem cells, or somatic stem cells while maintaining an undifferentiated state. Inventions include the use of one or a mixture of two and more fatty acid diglycerides represented by the general formula (I) (I), where at least one of R1, R2 and R3 are the same or different, represent acyl group derived from an unsaturated fatty acid having from 16 to 22 carbon atoms, and the remaining one means a hydrogen atom or where one of R1, R2 and R3 means an acyl group derived from a saturated fatty acid, one of R1, R2 and R3 represents an acyl group derived from an unsaturated fatty acid having from 16 to 22 carbon atoms, and the remaining one means a hydrogen atom.EFFECT : invention allows to have an effective influence on maintaining a non-differentiable state and stimulating the proliferation of stem cells.11 cl, 4 tbl, 3 ex