Ultrasonically activated scalpel (UAS) is a surgical device utilizing ultrasonic energy to cut and coagulate tissues simultaneously. The actions and features of UAS are considerably different from those of conventional ultrasonic cavitational aspirators (UCA) that have been used frequently in the neurosurgical field. The UAS has been used routinely in a number of general surgeries, including laparoscopic surgeries and open surgeries of the lung and liver. However, neurosurgical application of UAS has not been reported. We used UAS in surgical resection of intracranial tumors consisting of five meningiomas, two gliomas, and one metastatic brain tumor, and monitored thermal changes in tissues using thermoencephaloscopy to investigate the possibility of heat injury by UAS. It was used to achieve both dissection of the attachment of meningiomas and internal decompression of the tumors and allowed efficient resection of various tumors with minimal bleeding by adjustment of the combination of coagulation and cutting powers at five different positions. The attachment of meningiomas was coagulated and cut easily and safely by UAS. Moreover, infrared thermographic study showed that the degree of temperature increase and the area of elevated temperature were extremely limited in UAS. The current study suggests that it is a promising device in neurosurgery.