Provided are a composition and a sheet, including a mesenchymal stem cells-hydrogel-biodegradable support or a mesenchymal stem cells-hydrogel-nondegradable support and a preparing method thereof. More specifically, in the sheet including a mesenchymal stem cells-hydrogel-biodegradable support or a mesenchymal stem cells-hydrogel-nondegradable support according to the present invention, the high-active mesenchymal stem cells may be applied to a wounded part of a patient with epidermolysis bullosa as it is without isolation using proteases, and in the culturing, an extracellular matrix such as collagen, laminin, fibronectin, and elastin secreted from the mesenchymal stem cells is wholly present on the hydrogel to have an advantageous effect that skin reproduction and re-epithelization abilities are significantly excellent as compared with conventional dressing agents used for epidermolysis bullosa.