To determine a joint target value vector θ of a redundant robot on which a joint number is (n), a degree of a tip target value vector X is (m) and (n>m), by a few calculation load.

The vector X is divided into a plurality of partial vectors. Priority is imparted to the respective partial vectors. A linear relational expression between the respective partial vectors and the vector θ is determined. One priority (k) is selected, and "whether or not there exists an area where the whole partial vectors having priority higher than the selected priority (k) can be executed under a restriction condition of the linear relational expression and an inequality relational expression" is determined (S14 and S15). Its processing is executed to a partial vector of different priority, and on a partial vector having the lowest priority among the partial vectors determined that the area exists, a solution of a convex secondary plan method for minimizing an objective function C2 under the restriction condition is determined (S21). The determined solution is determined as a robot vector θ (S22).