The present invention provides a device and a method for detecting obstacles, which comprises a camera used for continuously capturing a first image and a second image at different time points; a calculator configured to calculate the movement distance and the running capacity of a vechile through comparing the two images; a running capacity compensator configurted to compensate the running capacity of the first image based on the second image; and a difference calculator configured to obtain the movement distance of the vehicle based on the above calculation result, and calculate the difference of the second image with the compensated first image.