Embodiments of the present disclosure relate to a thin film transistor array substrate and a display device. Since a wavy structure is formed through heat treatment in a structure in which a first buffer layer made of an organic material, a second buffer layer made of a metal oxide and a third buffer layer made of an inorganic material are stacked, it is possible to provide a display device including an array substrate which has stretchable characteristics through the wavy structure while preventing a crack from occurring in the third buffer layer and preventing characteristics of thin film transistors disposed on the third buffer layer from degrading.