To improve the uniformity of a film thickness of a green sheet to become a silicon nitride ceramic, and also to appropriately perform the control of an orientation degree of particles and to easily manufacture a silicon nitride ceramic substrate having good characteristics.
A sheet-shaped form is maintained, as it is, in a raw sheet 14 even after a Mylar sheet 12 is wound up by a winding side roll 16 and a raw sheet is separated from the Mylar sheet 12 (separating step). The raw sheet 14 after the separating step passes a heating device 18 (heating step). The raw sheet 14 is heated again and a binder component contained in the heating device 18 is softened. A constant shape property is obtained by evaporating an organic solvent at the drying step in the raw sheet 14. The orientation of a -type silicon nitride particles progresses and a plane orientation degree in the silicon nitride ceramic substrate can be set at 0.4 by performing a rolling step at a softening temperature or above of the binder after that.