A temperature sensor includes a temperature detector, an element electrode wire, a lead wire, and an intermediate member. Each of the lead wire and the intermediate member is made of a Ni-based alloy or an Fe-based alloy. The element electrode wire and the intermediate member are welded together in such a manner that opposing surfaces, facing each other abut against each other to constitute an element-side weld. The intermediate member and the lead wire are welded together such that they overlap each other in a longitudinal direction Z to constitute a lead-side weld. The lead wire is extended closer to the temperature detector than the element-side weld is located. A gap between the element electrode wire and the lead wire at least in the longitudinal direction Z is filled with a filler. The element electrode wire, the element-side weld, and the lead wire are fixed to one another by the filler.