An airtight container manufacturing method includes the steps of (a) exhausting an inside of a container through the through-hole; (b) arranging a spacer along a periphery of the through-hole on an outer surface of the container the inside of which has been exhausted; (c) arranging a plate so that the spacer and the through-hole are covered by the plate and a gap is formed along a side surface of the spacer between the plate and the container outer surface; and (d) arranging the cover to cover the plate and bonding the cover and the container outer surface via sealant positioned between the cover and the container outer surface. The sealing includes hardening the sealant after deforming the sealant by pressing the plate with the cover so that the gap is infilled with the sealant.