A thin plate member has a uniform thickness of not less than 5 μm and not more than 100 μm, includes at least a ceramic sheet, formed by sintering. The thin plate member has plural convex portions protruding from one plane P of the thin plate member, and plural concave portions caved in from the plane P. Accordingly, the deflection amount obtained when the thin plate member is supported at a predetermined support section of the thin plate member in a direction orthogonal to the plane P is smaller than the deflection amount of a thin plate member that is flat without having convex and concave portions. Therefore, a thin plate member which is difficult to be deformed is provided.