The invention provides an incubator 1 wherein stackers 3 having a plurality of microplate accommodating portions are arranged in a chamber 11, and a microplate transport device 5 is arranged for transporting a microplate 31 within the chamber 11 and moving the microplate 31 into or out of a desired microplate accommodating portion. A camera 7 is provided on a position opposed to a microplate accommodating portion of an uppermost stage in the stacker 3. The camera 7 faces said microplate accommodating portion, whereby a sample on the microplate 31 can be photographed.