A planning system includes an input device which accepts at least a given planning problem and values of variables required to solve the given planning problem; a display device which provides a visual display of an optimum plan obtained for the given planning problem; and a planner device which prepares an objective function representing items to be averaged and designs a plan to minimize a value of the objective function. The planner device includes an initial plan reader which reads an initial plan; an objective function value operation unit which calculates an objective function value of the initial plan; a reproduction unit which generates random numbers to a set composed by elements contacting to boundary planes of divided subsets, wherein the random numbers include a range of number of contacting elements and an equally-opportunity-selectable distribution, select at least one element based on the random numbers, equal-opportunity-selecting one of the subsets to which element contacts, and schedule the plan such that the selected element is rendered to belong to the selected subset; a plan renewal unit which compares the objective function value of the current plan with the objective function value of the previous plan to determine the plan having a smaller objective function value as an optimum plan; and a control unit which provides a visual display of an optimum plan on the display device.