The objectives of this research are to get empirical fact about cost of quality differences before and after ISO 9000 certification o n manufacturer companies. Cost of quality is cost which occur from unconformance with standard or bad quality. Cost of quality statement is a tool of successful ISO 9000 implementation.

This research is descriptive study which gives explanation about problems and hypotheses testing. This research use purposive sampling method by conforming o n several objectives or criterion. The sampling method resulting 22 manufacture companies with ISO 9000 certification listed in Jakarta Stock Exchange. The data collected from companies’ financial statement which grouped into several periods. In analyzing data, the researcher used descriptive statistics by paired sample t test.

The result of this study showed that there are significant differences in cost of quality before and after ISO 9000 certification. This can be viewed from significance value of each hypothesis (0.013, 0.046 and 0.019) which smaller than 0.05. It also can be viewed from t value (-2.726, -2.123 dan -2.540) which smaller than -t table value (-2.080).