An odor detection device includes an odor sensor for measuring an ambient odor, a fan that exhausts air around the odor sensor, and a substrate for controlling the fan and the odor sensor. Electric power supplied to the odor sensor, the fan, and the substrate is supplied from outside of the odor detection device, the substrate includes a connection unit capable of transmitting and receiving data to and from an external device that is a device separate from the odor detection device, and the fan is installed downstream of an airflow generated by the fan itself with respect to the odor sensor.