To provide a warmer/cooler for a human body, which prevents the risk of damaging and breaking, etc., when heating a gel material for warming/cooling, is used by warming up to temperature suitable for use without requiring labor and time, and is used by cooling down to temperature suitable for use even when cooling the gel material.

An exterior bag 1 internally sealing and enclosing the gel material has a structure including a confirming means 3 for confirming the both use temperatures for warming and cooling. It is adequate that the confirming means 3 includes: a confirming part 31 for warming, where a graphic or a character is printed with thermosensitive ink to change the color at internal temperature 40C to 80C on a surface of the exterior bag 1; and a confirming part 32 for cooling, where a graphic or a character is printed with the thermosensitive ink to change the color at internal temperature -25C to +15C. It is also adequate that the confirming means is obtained by allowing the gel material to be mixed with a thermosensitive base material for warming to change the color at prescribed temperature and a thermosensitive base material for cooling to change the color at prescribed temperature, or by enclosing the exterior bag 1 with a fabric bag 4 for preventing dew condensation.