A temperature sensor (100) includes a heat-sensitive element (21) having a thermistor sintered-body (22), an insulating support (31), an insulation sheath (41) and a housing tube (11). The insulating support (31) is in contact with the rear end of the heat-sensitive element (21) and the insulation sheath (41) is in contact with the rear end of the insulating support (31). The housing tube (11) accommodates the heat-sensitive element (21), the insulating support (31) and the insulation sheath (41). The housing tube (11) includes a sheath accommodation portion (14) which accommodates the insulation sheath (41) and a distal accommodation portion (13). The distal accommodation portion (13) is located toward the distal end of the housing tube (11) with respect to the sheath accommodation portion (14), is smaller in outside diameter than the sheath accommodation portion (14), and accommodates at least half of the insulating support (31) as measured from the axially distal end of the insulating support (31).