The temperature sensor 1 is equipped with a temperature sensitive device 2 to be disposed inside an exhaust pipe of an internal combustion engine, signal lines 31 connected at a top end side to the temperature sensitive device 2 and at a rear end side to leads for connection with an external circuit, an inner member 18 having a sheath pin 3 in which the signal lines 31 are disposed, and an outer member 13 disposed to cover at least a portion of an outer periphery of the inner member 18. The outer member 13 includes a fixed portion (rib 6) to be fixed to an upper wall of the exhaust pipe, a retainer portion 132 retaining the inner member 18, and an extending portion 131 formed closer to a top end side than the retainer portion 132. The extending portion 131 includes a clearance portion 19 disposed so as to have an air gap between itself and the inner member 18 and a front interference portion 133 disposed in a condition that a maximum air gap between the front interference portion 133 and the inner member 18 in a radius direction is 0.2 mm or less.