Reflection high-energy positron diffraction (RHEPD) is a new surface analysis tool having a capability to determine structure of adsorbed layers, surface Debye temperatures and metal dipole barriers with less disturbance from bulk. We have constructed a positron beam apparatus for RHEPD experiments and succeeded in observing RHEPD patterns and totalreflectionof positrons. In this article, we introduce the principle of RHEPD and some of its applications.