A surroundings monitoring device (200), which is provided on machinery in which the vehicle height changes, is provided with: multiple cameras (30) that image the surroundings thereof; a means for converting the original images (31) taken by the various cameras (30) to overhead viewpoints and generating overhead viewpoint images (35); a means for combining the respective generated overhead viewpoint images (35) to generate a bird's-eye image (300); a means for displaying the generated bird's-eye image (300); and a means for detecting the positions of the cameras. The bird's-eye image-generating means combines the images by adjusting the display region (e) for each overhead viewpoint image (35) on the basis of the respective detected camera height. It is thereby possible to always generate and display an accurate bird's-eye image (300) even when the vehicle height changes significantly.