This research aimed to determine the effect of self efficacy training on students mathematics learning motivation. Subject in this research were 25 students of class IX SMP N "X" Sleman Yogyakarta, which are divided into 13 students as the experimental group and 12 students as the control group. The data was collected using a scale of mathematics motivation to learn and scale of self efficacy. The research design used was pre post control group design. Analysis of the study were quantitative and qualitative analysis. Quantitative analysis using the Mann – Whitney test to determine mathematics learning motivation after the self efficacy training given. The qualitative analysis was done based on observation, interviews and worksheets. The results of the research were used pre-test and post-test, showed that there was increased mathematics learning motivation after training given by the value of Z = -3.740 dan p = 0,000 (p < 0,05). In the pre-test and follow-up, showed that there was increased mathematics learning motivation after two weeks of training given by the value of Z = 1.989 dan p = 0,047 (p < 0,05). The conclusion of this research is the self efficacy training can increased students mathematics learning motivation class IX SMP N "X".