This research aims at finding out the effect of bank internal factors towards Non-Performing Loan (NPL). The internal factors of bank used in this study are credit expansion level, operational efficiency level, credit interest level, and the percentage of credit with problems in the previous period as dynamic effect. The research is very importantdue to thecondition that the ratio of NPL owned by the bank group tend to increase.Compared to previous studies (especially thosewhich took the case in Indonesia), this study had some strengths in terms of bigger sample size(using quarterly data of 97 banks during 2013 until 2015)and the use of Generalized Method of Moment(GMM) modelto analyze the effect of bank internal factor towards NPL.Based on theGMM model analysis, it can be concluded that the level of credit expansion, operational efficiency, credit interest and the percentage of credit with problems in aquarterly period ahead would give positive effect towards NPL in the following quarterly period. Meanwhile, the percentage of credit with problems in two quarterly periodsahead would give negative effect towards NPL in the followingquarterly period.