Proposed is a flexible cover window having a folding part, the cover window being a glass-based cover window for a flexible display and including: a plane part provided by corresponding to a plane area of the display, and a folding part provided by continuing to the plane part, by corresponding to a folding area of the display, and by being slimmed to be thinner than the plane part, wherein a depth of layer (DOL) of the plane part is larger than a depth of layer (DOL) of the folding part.