The present invention provides a temperature sensor in which the connection portion of a wire from a temperature sensitive element or a temperature measuring junction and a lead wire can be surely insulated even under a high temperature condition, the connection portion which is provided inside the temperature sensor. The temperature sensor (1) includes: a temperature sensitive element (90); a sheath member (20) provided on a rear end side of the temperature sensitive element, and including a pair of sheath core wires (21) connected to the temperature sensitive element, and a sheath outer tube(22) accommodating the sheath core wires inside an insulation material; a pair of lead wires (80) disposed on a rear end side of the sheath member, and directly or indirectly connected to the respective sheath core wires exposed more on a rear end side than the sheath outer tube; and glass-braided insulation covering portions (25) individually covering a pair of respective connection portions (23) of the sheath core wires and the lead wires, so as to insulate between the pair of the connection potions, in a rear end from the sheath outer tube.