There have been known a technique of controlling the posture of a manipulating member (end-effector) by rotating a general size arm using a general size bearing and a technique of performing a necessary process on a minute work in a working device by rotating an arm or tool along an arcuated guide (see, for example, Japanese Patent Laid-Open No. 7-256575).
In a conventional apparatus like those described above, if the distal end of an end-effector is not located on the rotation axis of a bearing or arcuated guide, the distal end of the end-effector moves out of the visual field or depth of focus of a microscope due to posture control operation. This makes it necessary to position the microscope and the distal end of the end-effector again. As described above, in a manipulator which manipulates a minute object, when the posture of the end-effector at the distal end is controlled, the manipulation target object often moves out of the visual field of the microscope. In a conventional manipulator having three degrees of rotational freedom, in particular, since the rotation axes corresponding to the respective degrees of freedom do not coincide with each other and do not cross at one point, the distal end of the end-effector tends to move out of the visual field or depth of focus of the microscope due to posture control operation. In such a case, the microscope and the distal end of the end-effector must be positioned again. This operation requires a long period of time.