PURPOSE: To obtain a thermocouple of a minute diameter, which does not cause disconnection of a strand, etc., by embedding the thermocouple strand covered with a high molecular material, into insulating powder, and plastically working it together with a shell body.

CONSTITUTION: A thermocouple strand 2 of constantan, etc. is covered with a tube 3 having a high molecular material quality, it is embedded into insulating powder 4, is drawn by a die roll, etc. together with a shell pipe body 5, and is roll-worked, by which a thermocouple 1 provided with the shell pipe body is obtained. In this way, the high molecular covering body 3 is compressed like 31 in figure, and the strand 2 is also reduced as to its diameter, but it is never broken down.