According to an embodiment, a surroundings recognition device includes an acquirer configured to acquire first road information including a road boundary near a host vehicle from map information on the basis of position information of the host vehicle, a recognizer configured to recognize a road boundary near the host vehicle on the basis of an output of an external environment sensor, and a determiner configured to determine that a first road boundary matches a second road boundary when the second road boundary included in second road information that is a recognition result of the recognizer is within a road boundary determination area based on a position of the first road boundary included in the first road information acquired by the acquirer. The determiner sets a size of the road boundary determination area on the basis of a predetermined condition.