To easily and surely manage the quality of food in cooking or at a point of time when the cooking is ended by providing a shape memory member deformed according to temperature.

The tip part 2 of an indicator body 1 is formed of a heat transfer material such as metal which senses the central temperature of a food. The temperature transmitted from the tip part 2 is detected by a detecting part 3, and an indicating part 5 is protruded from the upper end 6 of the body to notify a cook of the cooking end. Namely, the body 1 has a cylindrical form having a cavity part 7 containing the detecting part 3, the indicating part 5 and a support part 4 for supporting it, the detecting part 3 is formed of a shape memory alloy, and the support part 4 and the indicating part 5 are formed of heat insulating materials. The tip part 2 is inserted into the food so that the detecting part 2 reaches the food center part followed by cooking. When the food center part is heated to an optimum temperature for good taste, the shape memory alloy of the detecting part 3 is extended to protrude the indicating part 5 from the upper end 6, so that the cook can visually and easily detect the cooking end.