A ceramic multilayer substrate that includes a ceramic insulator layer, which includes a first layer, a second layer, and a third layer and in which the first layer is interposed between the second layer and the third layer, an inner pattern conductor, an outer pattern conductor, and outer electrodes. The ceramic insulator layer is interposed between the inner pattern conductor and the outer pattern conductor. The sintering shrinkage start temperatures of the second layer alone and the third layer alone in a green sheet state are higher than or equal to the sintering shrinkage stop temperature of the first layer alone in a green sheet state. The thickness of the ceramic insulator layer is 5.0 μm to 55.7 μm. The ratio of the total of the thickness of the second layer and the thickness of the third layer to the thickness of the first layer is 0.25 to 1.11.