A temperature sensor includes a temperature detecting section including a temperature-sensitive element, a cylindrical housing disposed on a proximal end side of the temperature detecting section, a connector member disposed on a proximal end side of the housing, and a buffer member which is elastically deformable and disposed between the connector member and the housing. The connector member includes a connector counter surface located on a side of the housing in an axial direction along a longitudinal axis of the housing. The housing includes a housing counter surface located opposite to the connector counter surface. The housing counter surface and the connector counter surface are separated from each other so that a gap is present therebetween. The buffer member is disposed deformably in the gap so that the connector member and the housing are movable relative to each other in the axial direction.