To suppress inflow of external air through a rack insertion opening while a sample rack is pulled out. An apparatus includes a housing, a temperature control space, and an air temperature control part. The housing has the rack insertion opening on one side surface for putting in and taking out the sample rack. The air temperature control part has an air intake portion for intake of air in the temperature control space, a fan for blowing air taken in from the air intake portion toward the sample rack accommodated in the temperature control space, and a cooling element provided to cool the air on a path of air taken in from the air intake portion. The air temperature control part is configured to reduce an amount of air flowing near the rack insertion opening while the sample rack is pulled out from the temperature control space as compared to while the sample rack is accommodated in the temperature control space, so as to suppress inflow of air through the rack insertion opening.