PURPOSE: To shorten calculation time for judging the branching conditions of a condition branching sentence provided with plural branches.

CONSTITUTION: When it is judged that rebel branching conditions continue in a branching condition judging means 13, the length of the calculation time required for judging the authenticity of the branching conditions is evaluated in a branching condition evaluating means 14 and a block condition branching sentence for which the orders of the branching conditions and basic blocks executed when the branching conditions are judged as true are replaced in an order from the one for which the calculation time is shortest is outputted from a block condition branching sentence replacing means 15. By bringing the branching condition for which the calculation time required for judging the authenticity is short to front when the rebel branching conditions continue in the condition branching sentence provided with the plural branches, the calculation time can be shortened.