An object is to provide a brain cooling device capable of cooling the brain sufficiently to the subcortical tissue in a short time and a brain cooling system including the device. The device includes a cuff 3 capable of storing therein a cooled fluid and placeable in the esophagus H1 of the patient H when inserted orally or transnasally, and a tube 2 provided so as to extend from the cuff 3 for infusing the fluid into the cuff 3 placed in the esophagus H1 from outside the body of the patient H and discharging the fluid from the cuff 3. The cuff 3 has flexibility so as to inflate or deflate in response to infusion or discharge of the fluid and is configured in such a manner that when the fluid is infused therein while placed in the esophagus H1, the cuff 3 that has been inflated comes into close contact with the inner wall H4 of the esophagus H1.
