PROBLEM TO BE SOLVED: To provide a temperature and humidity adjustment mechanism capable of extremely reducing an energy cost and a facility cost and also performing measurement with high accuracy.SOLUTION: A temperature and humidity adjustment mechanism includes: a hole 4 arranged at a part of a shield floor 3 in an anechoic chamber 2; temperature and humidity adjustment means 7 arranged outside of the anechoic chamber 2 so as to adjust temperature and humidity; a duct 9 connecting the temperature and humidity adjustment means 7 to the hole 4 so as to perform ventilation; a table 6 arranged between the hole 4 and a tested body 8 and formed of an insulation material; and a cover 5 formed of a transparent insulation material to cover the whole parts of the tested body 8, the hole 4, and the table 6. The table 6 and the cover 5 are detachable from the shield floor 3.