1. A foldable display apparatus that is adjustable between a folded configuration and an unfolded configuration, the foldable display apparatus comprising:a flexible display panel that is foldable;
a case comprising:
a first case that supports a first side of the flexible display panel; and
a second case that supports a second side of the flexible display panel;
an elastic piece connecting the first case to the second case, the elastic piece being substantially flat in the unfolded configuration;
a link member connecting the first case to the second case and comprising a concave-convex type single body metal sheet; and
a locking unit configured to prevent rotation of the first case and the second case in a folding direction when the foldable display apparatus is in the unfolded configuration.