Foldable display device

A foldable display device, comprising:

• a support structure;
• a lower stress adjustment structure, disposed on the support structure;
• an upper stress adjustment structure, disposed on the lower stress adjustment structure;
• a cover layer, disposed on the upper stress adjustment structure;
• and
• a function display structure, disposed between the lower stress adjustment structure and the upper stress adjustment structure, wherein a total thickness of the support structure, the lower stress adjustment structure, the upper stress adjustment structure, the cover layer and the function display structure is not greater than 750 micrometers, and the function display structure comprises:
• a driving layer;
• an electronic ink layer, disposed on the driving layer;
• a transparent conductive water-resisting layer, disposed on the electronic ink layer;
• and
• a sealant, surrounding the electronic ink layer and connecting to the driving layer and the transparent conductive water-resisting layer, wherein a thickness of the driving layer, a thickness of the electronic ink layer, a thickness of the transparent conductive water-resisting layer and a thickness of the sealant are not greater than 60 micrometers, respectively.