Since the introduction of frequent pattern mining, majority of the studies have been focused on algorithmic efficiency. Many algorithms return the mining results in textual forms -- i.e., a long textual list of frequent patterns. However, it is well established that visual representation can be more compact and more comprehensive to users in visually revealing frequent patterns than textual representation. Existing visualizers mainly focus on showing frequency information of every frequent pattern, and thus ignore relationships (e.g., prefix/extension) among the mined patterns. Inspired by the tree map representation of hierarchical data, we propose in this paper a space-filling visualizer called FpMapViz for showing frequency information of every frequent pattern as well as prefix/extension relationships among the mined patterns.