Non-Existence of Invariant Curves for Some Billiard Systems A mathematical billiard consists of a planar region as a table and a ball moving in the table and reflecting on the boundary. By considering the moving as a discrete dynamical system, the billiard map is an area-preserving twist map. In this thesis, we show the result of non-existence of invariant curves for two different billiard maps. The first result presents the sufficient condition of the non-existence of invariant curves. In the second one, we prove the non-existence of invariant curves near the boundary for Halpern’s billiard, which has a convergent billiard orbit.