In this report, recently developed computer program named TB3D/FDM(Thermal Bridge Computa- tion by 2- or 3-Dimensional Finite Difference Method) is introduced. This program enables steady state heat transfer analysis of building exterior walls including thermal bridges. TB3D/FDM has a tool forming input data set for 3-D computations from DXF file, and employs TRAC3D (Thermal Radiation and Air-Convection in 3-Dimensional Air Cavity) computing thermal resistance of 3-D air cavities. Application process of TB3D/FDM is described, and calculation examples of temperature distribution and condensation risk judgment are shown.