An apparatus and a method for detecting an obstacle are provided. The apparatus includes a memory configured to store program instructions and a processor that is configured to execute the program instructions. The program instructions when executed are configured to compensate a position of a second image based on a first image based on a moving distance of a vehicle between the first image and the second image captured at different times and respectively generate a difference image based on a difference between the first image and the second image and between the first image and the second image in which the position is compensated. In addition, binarization is performed of the difference image and a synthetic image is generated for the two difference images. Then, the obstacle is detected by selecting a pixel corresponding to an area where the bit value is detected from the synthetic image.