The amount and complexity of data accumulated in electronic health record (EHR) is quite large, and the quantity of information that clinicians can examine and handle is very limited. Thus, it is necessary to enhance the accessibility of EHR by improving the user experience (UX). To apply information visualization that turns EHR data into an understandable visual format, we propose following five screen design principles when designing UX interfaces. #1: One view should contain single patient data. #2: Data should be summarized or titled for overview and details should be given on-demand. #3: Data should be displayed in time-series. #4: Data should be categorized by primary type. #5: More data should be displayed at the same time. Three screen designs are plausible utilizing the above-mentioned principles. To measure the UX of screen designs and validate the design principles, we built an EHR viewer system that has three windows corresponding to these screen designs and had it tested by medical staff. The results of the test revealed that the UX of the screen design is proportional to the number of design principles that the screen design incorporates. It shows that the proposed screen design principles improve the UX of EHR.