An environmental evaluation installation including an evaluation chamber 1 isolated from outer space by isolation walls 2, minute substance supply means 3 configured to supply a microorganism into the evaluation chamber 1, a minute substance removing means 4 configured to supply removal particles for removing the microorganism into the evaluation chamber 1, and a minute substance collecting means 5 configured to collect the microorganism in the evaluation chamber 1, and which is characterized in that many air supply holes 21 are provided for almost the whole surfaces of the isolation walls 2 except at least the floor surface of the isolation walls 2 and that air is made to flow into the evaluation chamber 1 from the air supply holes 21.