Background: To investigate the preoperative clinical and radiological factors that predict the development of a postoperative intraabdominal abscess (IAA) in patients with acute appendicitis who were treated by laparoscopic appendectomy (LA). Methods: Two hundred sixteen patients with pathologically proven acute appendicitis underwent LA between January 2013 and March 2018 in our department. Of these, 147 patients were diagnosed with complicated appendicitis (CA) (CA group), while the other 69 patients were diagnosed with simple appendicitis (SA) (SA group). We compared the perioperative clinical and radiographic factors between the two groups and investigated the predictive factors of postoperative IAA. Results: Sixteen patients developed postoperative IAA in the CA group, while no patients did in the SA group. The univariate analysis revealed that time from onset to surgery more than 3 days (p = 0.011), the preoperative CT finding of periappendiceal fluid (p = 0.003), abscess (p < 0.001), and free air (p <0.001), operation time more than 120 minutes (p = 0.023) and placement of a drainage tube (p <0.001) were significantly associated with the development of IAA. Multivariate analysis revealed that the preoperative CT finding of free air was independently associated with the development of IAA (p = 0.007, odds ratio = 5.427). Conclusions: IAA was developed predominantly in the patients with CA. Preoperative CT findings of free air was found to be an independent predictor for the development of IAA. Surgeons should be meticulous in managing the postoperative course of patients with this finding.