A temperature sensor including a temperature sensing element (102) having a temperature sensing unit (103) and a pair of device electrode wires (104) extending from the temperature sensing unit; a sheath member (106) including a sheath wire (108) connected at a junction (110) to one of the device electrode wires and a sheath outer pipe (107) retaining the sheath wire in an insulating material (114); an inner tube (112) which has a bottomed cylindrical shape, the inner tube accommodating the temperature sensing element and the junction in a bottom portion side of the inner tube serving as a leading end of the temperature sensor, and extending in an extension direction of the device electrode wire and the sheath wire; and an outer tube (120) which has a bottomed cylindrical shape including a gas inlet hole (122a, 122b, 122c), the outer tube covering the inner tube, and being spaced, from the inner tube on a leading end side of the junction when viewed in a direction perpendicular to an axial direction of the inner tube.