1. A vehicle surroundings monitoring apparatus for performing an object recognition on an object located in the vicinity of a vehicle on the basis of an image captured by an infrared camera mounted in the vehicle, comprising: a structure recognition unit that detects whether a featured image portion group is included in the captured image, the featured image portion group including: i) first and second high luminance image portions lined up side by side vertically or horizontally and a third high luminance image portion located below the first and second high luminance image portions, and ii) a feature indicating that a similarity of one of a luminance distribution and a shape between the first high luminance image portion and the second high luminance image portion is higher than between the third high luminance image portion and at least one of the first and second high luminance image portions, wherein upon detecting the featured image portion group in the captured image, the structure recognition unit determines that at least the third high luminance image portion is an image of a component of a traffic signal structure.