An attachment structure of temperature sensor includes: a temperature sensor for attached to a single battery and detecting a temperature of the single battery; a temperature measuring element provided in the temperature sensor and detecting the temperature of the single battery; a sensor body provided in the temperature sensor and integrally formed with the temperature measuring element; a housing holding case provided with the single battery, having a engagement part engageable with the temperature sensor, the housing holding case for housing the temperature sensor; an elastic part having an arm shape, projected from the sensor body, and engageable with the engagement part; and a flat part provided in the elastic part, and pressing a pressing surface of an attachment tool against the elastic part when the temperature sensor is housed in the housing holding case.