A method of manufacturing an electrostatic chuck heater, comprising: a base composed of an alumina sintered body; an electrostatic electrode which is embedded in an upper part of the base and contains a conductive material; and a heater electrode which is embedded in a lower part of the base and contains a conductive material, wherein the base includes: a dielectric layer between the electrostatic electrode and an upper surface of the base; a substrate layer between the electrostatic electrode and heater electrode; and a supporting layer between the heater electrode and a lower surface of the base; wherein the diffusion area ratio which is the ratio of the area of the conductive material of the dielectric layer to the total area near the electrostatic electrode is not more than 0.25%; the diffusion area ratio being the ratio of black part in a cross-sectional region in binarized image data, which cross-sectional region is 300μm by 850μm and is adjacent to the electrostatic electrode, with the 850μm long side of the cross-sectional region adjacent to the electrostatic electrode; by the steps of (i) applying a conductive paste containing a binder to an upper surface of a substrate-forming alumina sintered body which is to be said substrate layer to print the electrostatic electrode; (ii) applying a conductive paste containing a binder to the lower surface of the substrate-forming alumina sintered body to print the heater electrode; (iii) calcining the substrate-forming alumina sintered body having said conductive pastes (43, 45) applied thereto at a temperature of 450 to 1000°C; (iv) after step (iii) and before sintering of the alumina sintered body which has been calcined in step (iii) with said conductive pastes applied thereto, pressing alumina powder and the substrate-forming alumina sintered body in its state of having been calcined in step (iii) with said conductive pastes applied thereto, with the alumina powder placed above the electrostatic electrode and below the heater electrode; (v) after step (iv), sintering the alumina sintered body and said pressed alumina powder placed above the electrostatic electrode and below the heater electrode. a base composed of an alumina sintered body; an electrostatic electrode which is embedded in an upper part of the base and contains a conductive material; and a heater electrode which is embedded in a lower part of the base and contains a conductive material, wherein the base includes: a dielectric layer between the electrostatic electrode and an upper surface of the base; a substrate layer between the electrostatic electrode and heater electrode; and a supporting layer between the heater electrode and a lower surface of the base; wherein the diffusion area ratio which is the ratio of the area of the conductive material of the dielectric layer to the total area near the electrostatic electrode is not more than 0.25%; the diffusion area ratio being the ratio of black part in a cross-sectional region in binarized image data, which cross-sectional region is 300μm by 850μm and is adjacent to the electrostatic electrode, with the 850μm long side of the cross-sectional region adjacent to the electrostatic electrode; by the steps of (i) applying a conductive paste containing a binder to an upper surface of a substrate-forming alumina sintered body which is to be said substrate layer to print the electrostatic electrode; (ii) applying a conductive paste containing a binder to the lower surface of the substrate-forming alumina sintered body to print the heater electrode; (iii) calcining the substrate-forming alumina sintered body having said conductive pastes (43, 45) applied thereto at a temperature of 450 to 1000°C; (iv) after step (iii) and before sintering of the alumina sintered body which has been calcined in step (iii) with said conductive pastes applied thereto, pressing alumina powder and the substrate-forming alumina sintered body in its state of having been calcined in step (iii) with said conductive pastes applied thereto, with the alumina powder placed above the electrostatic electrode and below the heater electrode; (v) after step (iv), sintering the alumina sintered body and said pressed alumina powder placed above the electrostatic electrode and below the heater electrode. (i) applying a conductive paste containing a binder to an upper surface of a substrate-forming alumina sintered body which is to be said substrate layer to print the electrostatic electrode; (ii) applying a conductive paste containing a binder to the lower surface of the substrate-forming alumina sintered body to print the heater electrode; (iii) calcining the substrate-forming alumina sintered body having said conductive pastes (43, 45) applied thereto at a temperature of 450 to 1000°C; (iv) after step (iii) and before sintering of the alumina sintered body which has been calcined in step (iii) with said conductive pastes applied thereto, pressing alumina powder and the substrate-forming alumina sintered body in its state of having been calcined in step (iii) with said conductive pastes applied thereto, with the alumina powder placed above the electrostatic electrode and below the heater electrode; (v) after step (iv), sintering the alumina sintered body and said pressed alumina powder placed above the electrostatic electrode and below the heater electrode.