Incubator

An entry of air from the outside of an incubator into an incubation room is prevented. The incubator comprises an adiabatic box main body having an opening on a front face thereof, an adiabatic door mounted to the adiabatic box main body to be opened/closed, a transparent inner door which closes the opening to be opened, and a storeroom surrounded with the inner door and the adiabatic box main body to incubate samples such as cells or microbes. The adiabatic box main body comprises a metal outer box, a metal inner box, a heat insulating material arranged in the outer box between the outer box and the inner box, and an air layer arranged more inside than the heat insulating material. Pressure of the storeroom is set higher than that of an outside space of the incubator.