Provided are an apparatus and method for generating an acceleration structure in a ray tracing system. The method of generating an acceleration structure includes splitting, at an acceleration structure generator, a space comprising a three-dimensional (3D) object into a plurality of sub spaces, calculating costs for traversing the plurality of sub spaces based on occlusion information of primitives in the plurality of sub spaces, selecting the plurality of sub spaces that minimize the costs for traversing, and generating an acceleration structure based on setting the selected plurality of sub spaces as nodes.