A resin multilayer substrate includes a resin structure formed by laminating a plurality of resin layers and disposed components. Built-in components are embedded within the resin structure and a mounted component mounted on a surface of the resin structure. The resin structure includes a flexible part in which a first lamination number of the resin layers are laminated and a rigid part in which a second lamination number of the resin layers is laminated. The second lamination number is larger than the first lamination number. When viewed in a plan view, the flexible part has a shape which is not a rectangle, and a disposed component which is closest to a boundary line between the flexible part and the rigid part is disposed such that a side thereof which is closest to the boundary line is parallel to the boundary line.