Objective: Energy devices are frequently used in minimally invasive surgeries (MIS). For MIS involving gynecologic malignancies, energy devices should be used cautiously to prevent thermal injuries to nearby organs. We evaluated monopolar electrosurgery devices and measured increases in temperature in the tissue and device. Methods: Briefly, the surface of a porcine tissue was incised using short and long activation times. Subsequently, the maximum temperature at the tip of the monopolar device, the cooling time required to reach a temperature of 60 {}^{\circ }C, and the maximum tissue temperature were recorded. Results: Longer activation time was correlated with a higher tip temperature. With all activation times, there was an increase in the tip temperature that exceeded 100 {}^{\circ }C. The cooling time to reach 60 {}^{\circ }C was faster with the short activation times than with the long activation times. Even with the same output, the temperature decreased faster in the coagulation mode, suggesting that the cooling times were shorter with lower outputs. The tissue temperature dropped to 60 {}^{\circ }C or less within 1 s in the cut mode but required approximately 2 s in the coagulation mode at 40 W. The temperature of the dissected tissue increased to 60 {}^{\circ }C or higher; the cooling time was longer with high output and in the coagulation mode. Conclusions: We revealed that the activation of the monopolar device under routine use conditions exceeded a temperature of 100 {}^{\circ }C. Additionally, the temperatures of the tip and tissue were significantly higher in proportion to the output and time. For MIS involving gynecologic malignancies, careful attention is necessary to avoid thermal injury.