A resin substrate includes an insulating base material including opposing first and second main surfaces, at least one of which is parallel or substantially parallel to each of an X-axis direction and a Y-axis direction. The insulating base material is divided into first and second sections arranged in the X-axis direction. The first section includes, when evenly divided into three in a Z-axis direction, a first region closest to the first main surface, a second region closest to the second main surface, and a third region between the first region and the second region. A degree of resin molecular orientation in the first region in the Y-axis direction is greater than a degree of resin molecular orientation in the second section of the insulating base material in the Y-axis direction.