PURPOSE: To draw out the capacity of a robot to the maximum and improve the working quality by controlling each freedom degree displacement of the robot to make a control specification to each direction in a space easily realizable according to the contents of robot operation.

CONSTITUTION: Specifications for robot operation are described with a coordinate system fixed to a working space (101), an operation control target in each coordinate axial direction and a coordinate axis round direction is clarified (102), and a robot operation control capacity in each of these directions is found out as a function of attitude states of the robot (103). In succession, a control performance evaluation index as to working specifications in each direction corresponding to each of the robot attitude states is calculated (104), while the robot attitude state, where these weighted overall evaluation index values come to the largest value, is set down to an optimum attitude state (107), with which working is executed (108). With this constitution, since a proper robot attitude conformed to the work specifications is adoptable, working time is shortened and, what is more, working quality is improved.