To provide a micro temperature switch of a nanometer size usable in a wide temperature range in an environment of a micrometer size, and its manufacturing method.

Electrodes 3, 4 are mounted on both ends of a carbon nanotube 2 including a gallium pillar having a cavity 8 and put into an object whose temperature is to be measured. When a voltage is applied between the electrodes 3, 4, gallium is expanded following a temperature rise, and a sudden resistance change caused by disappearance of the cavity 8 is used as a temperature switch 1. Temperature measurement can be also performed. A carbon nanotube 6 including gallium before forming the cavity can be formed by heating gallium nitride powder at 1,300°C, while circulating methane gas and nitrogen gas.