A temperature sensor includes a thermo-sensitive element, a pair of element electrode wires electrically connected to the thermo-sensitive element, a sealing body covering the thermo-sensitive element and part of the pair of the element electrode wires, and a tablet formed with a pair of insertion holes through which the pair of the element electrode wires pass. An air bubble is formed at a position within the glass sealing body on a distal end side opposite to the tablet. The center of the air bubble is located within the outline of the thermo-sensitive element when viewed in the axial direction of the pair of the element electrode wires.