A sheathed thermocouple comprising: at least a pair of thermocouple wires having distal ends joined to each other to form a temperature measuring part; a metal sheath having a cylindrical shape having an opening at a proximal end and a closed distal end, the metal sheath accommodating the thermocouple wires without contact between the thermocouple wires and a cylindrical inner surface and contact between the thermocouple wires excluding the temperature measuring part, and a proximal end portion of each of the thermocouple wires being beyond the opening; inorganic insulating material powder filled in an internal space of the metal sheath excluding a proximal end portion of the metal sheath; a glass seal part made of a glass and filled in the proximal end portion of the metal sheath where no inorganic insulating material powder is filled, the glass seal part tightly sealing the opening of the metal sheath while allowing the thermocouple wires to pass therethrough so that the respective proximal end portions of the thermocouple wires extend out of the metal sheath; at least a pair of compensation lead wires having leading ends each connected to a proximal end of the proximal end portion of each of the thermocouple wires; a metal sleeve having a cylindrical shape having a distal end portion defining a connecting section connected with an outer peripheral surface of the metal sheath, and allowing a portion of the metal sheath closer to the proximal end than the connecting section, the proximal end portion of each of the thermocouple wires and the leading ends of the compensation lead wires to be in an internal space, the proximal end portions of the thermocouple wires and the leading ends of the compensation lead wires lying without contact with a cylindrical inner surface and contact between themselves excluding connection portions between the thermocouple wires and the compensation lead wires; and a glass filler part made of a glass having a lower softening temperature than the glass seal part, and filling an internal space of the metal sleeve. at least a pair of thermocouple wires having distal ends joined to each other to form a temperature measuring part; a metal sheath having a cylindrical shape having an opening at a proximal end and a closed distal end, the metal sheath accommodating the thermocouple wires without contact between the thermocouple wires and a cylindrical inner surface and contact between the thermocouple wires excluding the temperature measuring part, and a proximal end portion of each of the thermocouple wires being beyond the opening; inorganic insulating material powder filled in an internal space of the metal sheath excluding a proximal end portion of the metal sheath; a glass seal part made of a glass and filled in the proximal end portion of the metal sheath where no inorganic insulating material powder is filled, the glass seal part tightly sealing the opening of the metal sheath while allowing the thermocouple wires to pass therethrough so that the respective proximal end portions of the thermocouple wires extend out of the metal sheath; at least a pair of compensation lead wires having leading ends each connected to a proximal end of the proximal end portion of each of the thermocouple wires; a metal sleeve having a cylindrical shape having a distal end portion defining a connecting section connected with an outer peripheral surface of the metal sheath, and allowing a portion of the metal sheath closer to the proximal end than the connecting section, the proximal end portion of each of the thermocouple wires and the leading ends of the compensation lead wires to be in an internal space, the proximal end portions of the thermocouple wires and the leading ends of the compensation lead wires lying without contact with a cylindrical inner surface and contact between themselves excluding connection portions between the thermocouple wires and the compensation lead wires; and a glass filler part made of a glass having a lower softening temperature than the glass seal part, and filling an internal space of the metal sleeve.