A multilayer substrate comprises: a stack having a plurality of insulating base materials; a first component arranged within the stack at a first level in a thickness direction of the stack; a second component arranged within the stack at a second level different from the first level and arranged so that, in a plan view, at least a portion of the second component overlaps with a portion of the first component; and a supplementary member arranged to at least partly exist in a range, in a thickness direction, as high as or higher than a lower end of the second component and as high as or lower than an upper end of the second component, and in a plan view, within a region of a projected area of the first component not overlapped with the second component, the supplementary member having a rigidness higher than the insulating base materials.