PURPOSE: To increase degreasability and the degree of sintering and to obtain higher size-accuracy, by selecting alumina ceramic from the points of both crystalline property and grain diameter.

CONSTITUTION: In a method of manufacturing alumina multi-layer wiring boards by manufacturing alumina green sheets using alumina raw material powder, and by laminating and sintering the sheets, the alumina raw material powder used has peak half-value width of the α-alumina (104) face by X-ray diffraction after heating which is smaller by 0.0005 or larger than the haft-value width before the heat treatment, and the average grain diameter of the alumina raw material powder is 3μm or larger. The reason why the decrease of the half-value width should be 0.0005 or larger is that if the half-value width of the alumina raw material powder decreases to this extent after the sintering of the powder, the alumina raw material powder has sufficiently high activity and a good degree of sintering. And the reason why the average diameter of the alumina raw material powder should be 3μm or larger is that, when the powder is coarse to this extent, the pore diameters in the alumina green sheets become large and it becomes possible to increase degreasability.