This paper presents a static analysis that estimates un- caught exceptions in multithreaded Java programs. In Java, throwing exceptions across threads is deprecated because of the safet problem. Instead of restricting programmers? freedom, we extend Java language to support multithreaded exception handling and propose a tool to detect uncaught exceptions in the input programs.Our analysis consists of two steps. The analysis firstly estimates concurrently evaluated expressions of the multithreads in Java programs by the synchronization relation among the threads. Using this concurrency information, program?s exception flow is derived as set-constraints, whose least model is our analysis result. Both of these two steps are proved safe.