Recently, to prevent the corrosion of concrete structures, a new method of protection has been investigated. Polymer sheets coated with amorphous carbon (a-C:H) films to wrap concrete structures is one of the promising solutions. a-C:H films were synthesized by the atmospheric-pressure plasma-enhanced chemical vapor deposition method because large-area synthesis is beneficial for huge concrete constructions. The film is intended to be used outdoors; therefore, high weatherability of the film is required. In this study, the goal was to evaluate weatherability and clarify the mechanism of deterioration by light and water. After 100 h of weathering test, the film thickness decreased because of oxidization and decomposition. The films synthesized by filamentary dielectric barrier discharge have higher weatherability than those synthesized by glow dielectric barrier discharge. In addition, SiO:CH/a-C:H multilayer films have higher weatherability than single-layer a-C:H films. The results imply the possibility of the practical application of a-C:H films for the protection of concrete structures.