A display device includes a display panel, a functional layer disposed on the display panel, where the functional layer includes at least one selected from an optical layer and an impact absorbing layer, a window disposed on the functional layer, and an adhesive layer disposed between the functional layer and the window. The adhesive layer has a thermal decomposition starting temperature of about 300° C. or higher and a thermal decomposition peak temperature of about 350° C. or higher, where the thermal decomposition peak temperature is defined as a temperature at which an amount of weight loss or gas generation caused by the thermal decomposition is maximized.