To provide a surgical operation instrument with reduced force required for operation.

The surgical operation instrument including a housing 110, an endoscope portion 140 extending distally from the housing 110 and defining a first longitudinal axis, a drive motor which is disposed at least partially within the housing 110, a drive tube which is disposed in mechanical cooperation with the drive motor and is rotatable about a drive tube axis extending through the drive tube, a firing rod which is disposed in mechanical cooperation with the drive tube and at least a portion of which is translatable with respect to the drive tube, and end effector 160 which is disposed adjacent a distal portion of the endoscope portion and is in mechanical cooperation with the firing rod so that the firing rod drives a surgical operation function of the end effector 160.