Non Performing Loan (NPL) is a wrong one indicators that can explain how quality performance a conventional bank, due to high NPLs is indicator failure of the bank in bank too will experience decline earnings due diminished source income major conventional banks that is from distribution credit. Research this aim for explain about influence internal variable of bank in the form of Loan to Deposit Ratio (LDR) and Capital Adequacy Ratio (CAR) and external variable in bank the form of Gross Domestic Product and BI Rate to up down the ratio Non Performing Loan (NPL) of Conventional Bank in Indonesia on period year 2015 months January‟s up month June 2017. The research data used is secondary data obtained from Otoritas Jasa Keuangan, Bank Indonesia, and Badan Pusat Statistik. The data analysis model uses Error Correction Model (ECM). From the test assumption classic show that the data used in research normally distributed and no found variables that deviate from assumption classic so that data in available has meet requirement for using equation model multiple linear regression. Results research show that in long period CAR and GDP variables have positive influence and significant against NPL, Whereas LDR variable have positive influence that is not significant and the BI Rate variable has negative influence ones are not significant against NPL. In short period show LDR and BI Rate variables have negative effect however not significant against NPL, whereas CAR and GDP variables have positif effect however not significant against NPL. For lowered and keeping the NPL ratio is not too high, then the bank should improve performance management deep bank credit analyze costumers will receive loans.