A brain cooling device is provided to cool the brain sufficiently to the subcortical tissue in a short time. 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. A tube (2) extends 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).