Embodiments relate to a polyimide-based composite film, which comprises a base film comprising a polyimide-based resin; and a functional layer disposed on the base film, wherein when the side of the functional layer located opposite to the side in contact with the base film is referred to as a first side and when the side of the base film located opposite to the side in contact with the functional layer is referred to as a second side, the adhesiveness index represented by Equation 1 is 3.5 or less.