A temperature detection device that can facilitate attachment of a temperature sensor to a coil and can improve thermal responsiveness by a simple structure reduced in the number of components. Such a temperature detection device includes a temperature sensor including a thermosensitive body configured to detect temperature of a coil of a rotary electric machine to be mounted on a vehicle, and a metal bracket attaching the temperature sensor to the coil. The bracket includes a bracket main body clamping the coil by elastic force, and a joining portion joined to the temperature sensor. The bracket main body includes a clamping portion internally clamping the coil, and a heat collection portion that protrudes to outside of the clamping portion and is thermally coupled to the temperature sensor.