Recently, with increasing maintenance costs, studies on software quality are becoming increasingly important and widespread because high quality software means more easily maintainable software. Measurement plays a key role in quality improvement activities and metrics are the quantitative measurement of software design quality. In this paper, we introduce a graph based object-oriented software quality visualization tool called "E-Quality". E-Quality automatically extracts quality metrics and class relations from Java source code and visualizes them on a graph-based interactive visual environment. This visual environment effectively simplifies comprehension and refactoring of complex software systems. Our approach assists developers in understanding of software quality attributes by level categorization and intuitive visualization techniques. Experimental results show that the tool can be used to detect software design flaws and refactoring opportunities.