A ceramic multilayer substrate includes stacked ceramic layers; internal conductors which are stacked with one of the ceramic layers therebetween, and are arranged such that at least a portion of the internal conductors overlap each other in a stacking direction; and a constraining layer which is arranged on a layer different from layers on which the internal conductors are located. The constraining layer overlaps, in the stacking direction, an internal conductor-overlapping region where at least two of the internal conductors overlapping each other in the stacking direction, has a planar area not more than twice the planar area of the internal conductor-overlapping region, and contains an unsintered inorganic material powder. The constraining layer has a planar area not more than one-half the planar area of the ceramic layers. The constraining layer is arranged so as to entirely cover the internal conductor-overlapping region.