Undergraduate thesis, or known as Skripsi, is research project that some university students in undergraduate degree should do as one of the requirements to complete undergraduate degree. The existence of skripsi as the undergraduate degree requirement is established not only by the government regulation but also the university policy. This research investigated deeper about the influencing factors (the supporting and the inhibiting factors) faced by the students to finish skripsi writing. The methodology of this research used descriptive qualitat ive. Six undergraduate students who experienced and successfully finished their skripsi were interviewed to collect the data. This research examined the influencing factors according to psychological (students habits), socio-cultural (problems with supervisor and academic culture), and linguistic (grammar problem). The result showed that, the supporting factors for PBI UMY students to finish skripsi writing were identified as the psychological factors (setting a target, timeline-based working, good self-management, activeness, good relationship with the supervisor, family and friends), the socio-cultural factors (positive relationship with the supervisor, and the support from family and friends), and linguistic factors (high level of grammar mastery). In contrast, this result also found the inhibiting factors of PBI UMY students to finish skripsi writing that were identified as the psychological factors (poor self-management, no target setting, the distraction especially for working students, and de-motivation), the socio-cultural factors (uncooperative supervisor, xi bad influence from friends, and different perceptions between the supervisor and the examiner), and linguistic factors (poor grammar mastery level).