The purpose of this study was to compare the safety and efficacy of an electrothermal bipolar vessel sealing device (LigaSure™) and traditional electrical cauterization in laparoscopic myomectomy (LM). A total of 756 patients with symptomatic uterine myomas who underwent LM were reviewed retrospectively. A total of 225 cases of LM using LigaSure™ (LML group) were compared with a control group treated with traditional electrical cauterization (LME group) under propensity-matched analysis. Outcome measures for both groups were compared, such as operative time, blood loss (BL), complications, need for blood transfusion, hospital expenses, and hospital stay. Six subgroups were divided according to main myoma size and energy source. No cases required switching to abdominal myomectomy. The number of myomas removed, BL, need for blood transfusion, and complications were not significantly different, whereas hospital stay was longer in the LME group than in the LML group and total hospital expenses were higher in the LML group (p < 0.001). The overall operation duration was significantly longer in the LML group but was not significantly different for main myoma >10 cm (LML vs LME, 121.58 ± 41.77 vs 121.69 ± 44.95, p = 0.99); this likely reflects the operative efficiency on using LigaSure™ to manage large tumors. Significant linear correlations between myoma weight and operative time and BL were seen in both groups. Conventional diathermy is more effective for small-to-medium myomas. Use of the LigaSure™ was efficient for myomas >10 cm.