Existing methods for Japanese predicate argument structure (PAS) analysis identify case arguments of each predicate without considering interactions between the target PAS and others in a sentence. However, the argument structures of the predicates in a sentence are semantically related to each other. This paper proposes new methods for Japanese PAS analysis to jointly identify case arguments of all predicates in a sentence by (1) modeling multiple PAS interactions with a bipartite graph and (2) approximately searching optimal PAS combinations. Performing experiments on the NAIST Text Corpus, we demonstrate that our joint analysis methods substantially outperform a strong baseline and are comparable to previous work.