To provide a temperature sensor unit and a body core thermometer making it possible to produce in low costs. The temperature sensor unit (1) is used to measure a deep part body temperature Ti as a body core temperature of a testee. The temperature sensor unit (1) comprises at a measurement face side facing a body surface of the testee first-fourth temperature sensors (111-114) for measuring the body surface of the testee. Among the first and the second temperature sensors (111, 112), the first thermal resistor (121) is disposed only at the measurement face side of the first temperature sensor (111). Furthermore, the first temperature sensor (111) and the second temperature sensors (112) are disposed proximally such that a temperature Ti at the measurement face side of the first thermal resistor (121) becomes approximately equal to a temperature T2 measured by the second temperature sensor (112).