In order to enable non-shrinkage firing, the strength of a multilayer 
ceramic substrate is increased which is obtained by a method in which alternately stacking a base material layer and a constrained layer which is not sintered at the 
sintering temperature for the base material layer, and in a firing step, allowing the material of the base material layer to flow into the constrained layer while subjecting the base material layer to 
sintering, thereby achieving densification of the constrained layer. The base material layer and the constrained layer each include celsian, and the abundance of celsian is lower in the base material layer than in the constrained layer. In order to increase the strength of the base material layer, the addition of a Ti component, rather than an increased content of Al component which interferes with 
sintering of the base material layer, causes fresnoite to be deposited in the base material 
layers. The presence of fresnoite in the base material 
layers increases 
crystal grain boundaries in the base material 
layers, and thus prevents 
cracking, thereby allowing the strength of the multilayer 
ceramic substrate to be improved.