Different microstructures in the weld zone of a metal structure such as a fusion zone or heat affected zone are formed as compared to the parent material. Thus, the mechanical properties in the weld zone are different from those in the parent material. As the basic data for reliably understanding the structural characteristics of welded PCHE prototype made of SUS316L, the mechanical properties in the weld zone and parent material for a SUS316L plate are measured using an the instrumented indentation technique in this study.