A signal generating apparatus includes a spreading device that respectively spreads data using spreading code that is based on an initial phase; a multiplexing unit that code multiplexes the data spread by the spreading device; a calculating unit that calculates a peak of a signal resulting from code multiplexing by the multiplexing unit; a changing unit that changes the initial phase of the spreading device in a predetermined order; a determining unit that each time the initial phase is changed by the changing unit, determines whether the peak calculated by the calculating unit is at most a threshold; and a transmission control unit that outputs the signal, if the determining unit determines that the peak is less than or equal to the threshold.