The directed hypergraph (especially B-hypergraph) has hyperedges that represent relations of a set of source nodes to a single target node. Author-cited networks and cellular signaling pathways can be modeled as a B-hypergraph. In this paper every source node of a hyperedge in the shortest path p in a B-hypergraph is considered a participant of p. We propose a betweenness centrality in the B-hypergraph that measures the number of shortest paths in which a node participates. The algorithm for computing the approximated betweenness centrality scores is also proposed. Through various performance experiments such as attack robustness and reachability tests, we show that our proposed betweenness centrality is a more appropriate measure in real-world B-hypergraph applications than ordinary betweenness centrality.