Students' attitudes toward mathematics play a key role in their academic achievements. Still, concerns regarding the low grades in mathematics tests of engineering students have raised questions about the reasons for their poor performance. Prior research has mentioned the impact of engineering students' attitudes on their grades. Few studies have attempted to explore the factors that influence and form engineering students' attitudes toward mathematics. The current study aims to investigate the factors that affect freshman engineering students' attitudes toward mathematics using a qualitative research design. Interviews with 26 participants enrolled at Imam Abdulrahman Bin Faisal University (IAU) in Saudi Arabia provided insight into the students' experiences through survey questions. Thematic content analysis was used in this study to analyze the interviews. The results of the interview indicate that the freshman engineering students' attitudes are most affected by their fathers and their teachers. The causes that form students' attitudes toward mathematics can be divided into two parts: internal and external. The internal causes result from the students themselves, which include practice and preparation, assessments and grades, effect of English proficiency, and time management. The external causes include teachers' characteristics and parental support.