A temperature detecting apparatus is provided which is capable of suppressing disconnection of a thermocouple wire or positional deviation of a thermocouple junction portion caused by change over time. The temperature detecting apparatus includes: an insulation rod installed to extend in a vertical direction and including a through-hole in vertical direction; a thermocouple wire inserted in the through-hole of the insulation rod, the thermocouple wire including a thermocouple junction portion at an upper end thereof and an angled portion at a lower end of the insulation rod; and a buffer area installed below the insulation rod and configured to suppress a restriction of a horizontal portion of the angled portion upon heat expansion, wherein an upper portion of the thermocouple wire or a middle portion in the vertical direction are supported by the insulation rod.