In the structures of automobiles and ships which have engines for works, the vibration energies generated by the engines are transferred to dissipation parts through the structures which is welded and bolted with beams and plates. The vibration energies generated by resonance frequencies are the reasons of the resonance phenomena. To solve these problems, up to the present, we have studied to avoid the resonance, and add the higher damping characteristics. However, we need to understand the structural energy flows, to design the structures clearly which have the characteristic of welding. The object of this study is to make differences clear in the characteristics of structures which have some welded part on an homogenous flat plate. In this investigation, we study the flows of structural vibration energy experimently, and then, some knowledge for dynamic structural design is obtained.