In a multi-layer substrate, a glass cloth of a build-up layer is deformed toward a land below the land. A thickness of a resin layer of the build-up layer from the glass cloth to a surface adjacent to the land is set to be smaller than a dimension from the glass cloth to a front surface of a core layer. With the above configuration, a progress or an enlargement of a crack can be suppressed from a stage in which the crack is smaller. Therefore, the progress and the enlargement of the crack can be delayed. As a result, even if the crack is generated, an insulating property between the land and an inner layer wire is ensured, and the land and the inner layer wire can be restricted from being short-circuited.