An electronic control device incorporated in a vehicle includes: a sensor detection information acquiring unit that acquires detection information from a first external environment sensor and detection information from a second external environment sensor, the first external environment sensor and second external environment sensor being incorporated in the vehicle; a sensor detection information integrating unit that specifies a correspondence relationship between an environmental element indicated in detection information from the first external environment sensor and an environmental element indicated in detection information from the second external environment sensor; and a sensor detectable area determining unit that determines a relationship between a relative position and a detection capability at the first external environment sensor, based on a state of detection by the first external environment sensor of an environmental element detected by the second external environment sensor, the state of detection being indicated in the integrated detection information, and that based on the relationship, determines a detectable area for the first external environment sensor.