Management of blood component storage must be strictly controlled in accordance with the blood components storage management manual. Refrigerators used for storing blood bags should be equipped with a continuous temperature recorder and appropriate alarm systems. In the Blood Components Use Fact-finding Survey in Japan in 2021, however, it is reported that blood bags were sometimes stored in pharmaceutical or domestic refrigerators, especially in small-scale medical facilities or home transfusion where blood transfusion is not performed regularly. To investigate the actual internal temperature of blood components stored in such refrigerators, we measured the temperature distribution inside the cabinets and the internal temperature of simulated blood bags placed in various positions in of the cabinets. The lowest and the highest temperatures of blood bank-, pharmaceutical-, and domestic ( 'strong' setting) refrigerators were 2.4°C and 11.5°C, 0.2°C and 11.9°C, and −5.2°C and 13.1°C, respectively. The lowest and the highest internal temperatures of simulated blood bags placed in blood bank-, pharmaceutical-, and domestic refrigerators were 3.8°C and 5.8°C, 1.0°C and 3.9°C, and −4.8°C and 10.0°C, respectively. These results indicated that it is inappropriate to store blood components in refrigerators not equipped for blood banking. If such storage is temporarily unavoidable, it is recommended that blood bags should be placed in a position of stable temperature and that overcooling be prevented by avoiding direct cold airflow. It is also necessary to set up a continuous temperature-monitoring device with a chart recorder and an appropriate alarm system.