A thermistor includes a thermistor element, a protective film formed on the surface of the thermistor element, and electrode portions formed on both end portions of the thermistor element, in which the protective film is formed of silicon oxide, and, as a result of observing a bonding interface between the thermistor element and the protective film, a ratio L/L0 of a length L of an observed peeled portion to a length L0 of the bonding interface in an observation field is 0.16 or less.