An actuator main body (6) mounted on an operating bench (50) includes a main body base end housing (4) fixed to the operating bench (50), an elongated spindle guide section (3) having its base end connected with the main body base end housing (4), a distal end member (2) fitted to a front end thereof for alteration in attitude, and a tool (1) rotatably provided in the distal end member (2). Within the spindle guide section (3), a rotary shaft (22) for transmitting a rotation of a tool rotation drive source (41) to the tool (1) and an attitude altering member (31) for altering the attitude of the distal end member (2) are provided. Within the main body base end housing (4), an attitude altering drive mechanism (43) for selectively advancing or retracting the attitude altering member (31) when driven by an attitude altering drive source (42) is provided.