An optimum combination of a loop unrolling number and a circuit parallel number in a high-level synthesis is determined. A circuit synthesis information generation unit sets, as parameter candidates, a plurality of combinations of a loop unrolling number and a circuit parallel number to generate circuit synthesis information indicating a synthesis circuit obtained by high-level synthesis processing for each of the combinations. An optimum parameter determination unit calculates, for each piece of the generated circuit synthesis information, an estimation processing performance related to the synthesis circuit indicated by the circuit synthesis information, and determines an optimum combination of the loop unrolling number and the circuit parallel number based on the circuit synthesis information based on which a maximum estimation processing performance is obtained.