A high dynamic range (HDR) image generating apparatus and method is provided. The HDR image generating apparatus may set an auto-exposure time, a long exposure time, a short exposure time, and a reference exposure time. The auto-exposure time may be set to be shorter than the long exposure time, the short exposure time may be set to be shorter than the auto-exposure time, and the reference exposure time may be set to fall within a range between the auto-exposure time and the short exposure time. The image generating apparatus may obtain a first image with the long exposure time and a second image with the reference exposure time, may correct motion in the first image and adjust a dynamic range of the second image, and then may composite the resultant first and second images to generate a high dynamic range image.