A behavioral synthesis apparatus includes a acquisition unit, a scheduling unit and a generation unit. The acquisition unit acquires a behavioral level description describing an operation of a semiconductor integrated circuit. The scheduling unit separates the acquired behavioral level description into N stage descriptions, and makes a schedule in such a way that input/output operations and computations among the N stage descriptions are pipelined. The generation unit generates a register transfer level description based on the N stage descriptions and a result of scheduling performed by the scheduling unit in such a way as to form stage circuits respectively corresponding to the N stage descriptions and a state control circuit which controls possible 2N−1 stage control states of the semiconductor integrated circuit. The generation unit generates the register transfer level description in such a way as to inhibit the operation of a stage circuit which need not be operated.