Cement-based repair materials are generally used as concrete repair patches. However, these repair materials can generate cracks and shelling, and decreasing concrete structure durability. In this study, we carried out, among others, adhesive strength and water permeability tests to improve the durability of concrete structures repaired by the aforementioned materials, to clarify the properties of the interface between the concrete and the repair materials. Results showed that water permeability played an important role in the interface between the concrete and the repair materials. This evaluation makes it possible to improve the durability of repaired concrete structures.