Abstract This study tries to investigate factors affecting motivation of students towards learning English grammar at: in the case of South Gondar Zone Debre Tabor town High Schools, ANRS, and Ethiopia. To carry out this study descriptive survey method was employed. The sample composed of 107 sample grade 9th students were selected using lottery methods and 9 high school English teachers were selected through available sampling method for interview. Both qualitative and quantitative data analysis methods were employed in order to turn up at the results. The findings of the study revealed that in the area there are a number of motivational factors that affect learning English grammar in secondary high schools. The major factors are self-efficacy, active learning strategy, value of learningEnglish grammar, performance goals and learning goals related to motivation.Regarding to the most prevalent factors that affect the students’ motivation towards learning English grammar participation in English grammar lessons to perform better than other students, confident about understanding of difficult grammatical concepts in English, thinking that learning English grammar is important to solve problems because it stimulates their thinking, during an English grammar course feel happy and satisfied when able to solve a difficult problem. To improve students motivation in learning English grammar, the study recommendspraise students in classroom participation, using a variety of teaching methods, reward positive behavior inside or outside the classroom and participating all concerned bodies in teaching/learning English grammar situations, making students be competent in their ability to master grammar subject as a possible solution to enhance the motivation of students.