The purpose of the present invention is to provide an external environment recognition device which, when a cutting-in vehicle cuts in between a preceding vehicle and a host vehicle, recognizes the cutting-in vehicle as a vehicle on the basis of side surface information of the cutting-in vehicle. The external environment recognition device is characterized by having: a side surface extraction unit which, on the basis of the parallax between left and right images captured of a portion of another vehicle approaching the host vehicle, extracts side surface information of the other vehicle from the images; a rear surface search unit that searches for the rear surface position of the other vehicle on the basis of the side surface information; a shape fitting unit which, on the basis of the side surface information and the rear surface position, fits a rectangular parallelepiped shape that approximates the other vehicle in the images; and an other vehicle recognition unit that recognizes the other vehicle as the vehicle in front of the host vehicle by using the rectangular parallelepiped shape.