Purpose <p>Laparoscopic transabdominal preperitoneal inguinal hernia repair (TAPP) is useful for resident training. However, the association between the operative interval and skill acquisition remains unclear. We evaluated the learning curve of resident-performed TAPP and explored the association between the operative interval and operative time changes.</p> Methods <p>We retrospectively analyzed 67 consecutive TAPP cases performed by a single surgical resident. A cumulative sum (CUSUM) analysis was based on the adjusted operative time, with bilateral cases weighted by 0.6. Breakpoints were estimated using segmented regression, and the relationship between the operative interval and the change in adjusted operative time between consecutive cases (ΔTime) was assessed using exploratory analyses.</p> Results <p>A CUSUM analysis estimated breakpoints at 16.0 (95% CI, 13.7–18.3) and 38.1 (95% CI, 36.5–39.7) cases. BMI showed a weak negative correlation with operative duration. The adjusted operative time decreased across the learning, proficiency, and competency phases. Exploratory LOESS curves suggested a possible non-linear relationship between operative interval and ΔTime, with 8–14-day intervals showing a tendency toward a greater reduction during early phases. However, the differences among the interval groups were not significant.</p> Conclusion <p>Resident-performed TAPP exhibited a three-phase learning curve. Case selection and operative interval may be associated with operative time changes, although these findings remain exploratory.</p>