Recently, the notion of National Innovation System (NIS) has attracted considerable attention as a key driver of the economic success. Amongst others, the Northeast Asian countries deserve highlight as central cases of NIS. This research attempts to examine inter-industrial knowledge flows and structure among Northeast Asian countries. To this end, Korea, Japan and Taiwan are selected and the patent citation data, a proxy of disembodied knowledge flows, from United Stated Patents and Trademark Office (USPTO) are employed for cluster analysis and network analysis. Some meaningful findings are presented and distinctive characteristics of respective countries are contrasted.