Multilayered ceramic substrate production method

A multilayered ceramic substrate production method comprising:

• providing a first green ceramic sheet having an opening for forming a cavity having a bottom surface, a second green ceramic sheet having no opening at least at a position corresponding to said opening, and a shrinkage-reducing sheet containing an inorganic material which is not fired at a firing temperature at which the first and second green sheets can be fired;
• producing a green sheet stack having a cavity defined by said opening by stacking said first green ceramic sheet and said second green ceramic sheet so that an aperture of said cavity is placed on at least one end face in a sheet-stacking direction of the resulting green sheet stack, and placing said shrinkage-reducing sheet so as to close said aperture of said cavity and to cover said end face in the sheet-stacking direction of said green sheet stack;
• pressing said green sheet stack in the sheet-stacking direction so that a pressing force is exerted toward the bottom surface of said cavity, so that said shrinkage-reducing sheet is cut along the rim which defines said aperture of said cavity and so that a shrinkage-reducing sheet piece formed of a part of said shrinkage-reducing sheet is placed on said bottom surface of said cavity;
• and
• firing said green sheet stack in a state in which said shrinkage-reducing sheet piece is on said bottom surface of said cavity at a temperature at which a ceramic material contained in said first and second green ceramic sheets is fired and at which the inorganic material in said shrinkage-reducing sheet is not fired.