MISA - a general purpose FEM program. This paper describes the Mitsui Structural Analysis Program System (MISA) using the Finite Element Method, which has been developed and improved by Mitsui Engineering and Shipbuilding Co. Ltd. The program system is designed to have high performance pre- and post-processors and has functions for heat conduction analysis and stress analysis. The paper gives a description of the program system in brief terms, and of its functions of extensive input data generation and output editing in combination with the Multi-level Substructure Method. Two examples which illustrate these features more concretely have been chosen for inclusion in this paper.