Objective: This study aims to make the evaluation methodology of User Safety or Product Usage Safety during usability testing of product by FMEA (Failure Mode and Effect Analysis). Background: In order to set up the methodology, the concept of Product Safety was reviewed by its definition and laws in force. And Usability Testing by user was researched mainly in a point view of its process. And also, for measuring User Safety or Product Usage Safety, FMEA was checked by possibly acceptable analyzing or measuring technic. Method & Results: In study, for the first time, the concept of the Product Usage Safety was defined because this concept was not defined before and must be needed in order to get the idea of User Safety derived by Usability. And then, an evaluation method for the Product Usage Safety was designed through the process of Usability Testing. That has two stage; first, a checklist was achieved by modified FMEA that was designed for checking the functional steps of tasks, (Tasks were given to user in Usability Testing in order to evaluate Usability of a product), and next the checklist was examined by researcher during whole Usability Testing. Finally, observed items on checklist that ruined the Product Usage Safety were determined, and those must be re-designed to get the Product Usage Safety. Conclusion and. Application: From this current research, Product Usage Safety can be measured by modified FMEA during Usability Testing but this research must be experimented in Usability Testing, and further research and analysis must be needed for practical use in many ways.