A triaxial tool unit includes three actuators 3, 4, 5 which operate in three-axis directions orthogonal to one another, a tool holder 7 provided at an intersection on axial lines in operating directions of the actuators 3, 4 and 5, and sensors 8, 9 and 10 which measure displacement amounts in the operating directions of the actuators 3, 4 and 5, and has a structure in which the sensors 8, 9 and 10 are disposed so that extension lines in respective sensing directions intersect with one another at one point.