The investigation of the environment in the stone chamber of the Torazuka tomb, Ibaraki prefecture, during 3 successive years, 1983-1985, showed the following results: 1) Between October and December, the innermost part of the stone chamber is dry, and the entrance to the chamber is wet, whereas between March and May the former is wet and the latter dry. 2) The northern part of the tomb showed a greater cooling as compared to the other parts of the tomb in winter. 3) The annual temperature difference at the inside of the double glazing is about one-fourth of that of the outside of the outermost door, indicating a large thermal insulation effect as a result of the combination of three doors and double glazing. -- AATA