A temperature sensor includes a sensor element including a thermosensitive body, a protection tube accommodating the thermosensitive body part of the sensor element, and a filler filling a space between the protection tube and the sensor element inside the protection tube. The sensor element includes a first covering layer made of a first electrical insulator, the first covering layer covering the thermosensitive body, and a second covering layer made of a second electrical insulator, the second covering layer covering the first covering layer. The first covering layer has elastic modulus smaller than elastic modulus of the second covering layer.