The aim of this study is the development of method to confirm three porcine disease viruses, namely PRRSV, PCV2, and SIV using one-step RT-PCR. Including internal control, primers were designed in order to amplify five targets; PRRSV for North American (NA type), PRRSV for European (EU type), SIV (subtype H1N1, H1N2, and H3N2) and PCV2. PCR test was performed using all primer mixture to detect three porcine diseases. Previous porcine disease diagnosis products were used to only one disease. This means one product can detect only one disease type. Therefore, test price is expensive and this takes long time for detecting three type of diseases. It is also considered extra gene amplification reagent should be used for RNA virus and DNA virus. However, in this study, complex infection can be detected with only single test using the one-step RT-PCR premix that can simultaneously amplify using RNA and DNA viruses. Based on this results, the expected diagnosis testing time and prices can be reduced for the market.