Through-hole sealing structure and sealing method, and transfer substrate for sealing through-hole

A sealing structure comprising:

• a set of base members forming a sealed space;
• at least one through-hole which is formed in at least one of the set of base members, and communicates with the sealed space;
• and a sealing member that seals the through-hole,
• the sealing structure including an underlying metal film on a surface of the base member in which the through-hole is formed, the underlying metal film including a bulk-like metal including at least one of gold, silver, palladium and platinum, the underlying metal film being formed so as to surround the peripheral part of the through-hole,
• the sealing member sealing the through-hole while being bonded to the underlying metal film,
• the sealing member including:
• a sealing material which is bonded to the underlying metal film, and includes a compressed product of a metal powder of at least one selected from gold, silver, palladium and platinum, the metal powder having a purity of 99.9% by mass or more;
• and
• a lid-like metal film which is bonded to the sealing material, and includes a bulk-like metal including at least one of gold, silver, palladium and platinum,
• the sealing material including:
• an outer periphery-side densified region that is in contact with the underlying metal film;
• and a center-side porous region that is in contact with the through-hole,
• the densified region having a porosity of 10% or less in terms of an area ratio at any cross-section.