An information obtaining apparatus capable of obtaining information about a blood vessel with high accuracy includes a first unit configured to obtain three or more image data pieces different in imaging conditions, a second unit configured to obtain a first index value of a first region and a second index value of a second region, a third unit configured to select a pair of the image data pieces from the three or more image data pieces using the first index value and the second index value of the image data, and a fourth unit configured to obtain information about a blood vessel using the selected pair of the image data pieces.
