A notification sound control unit (10) of an approaching vehicle audible system (100), generating a signal for a notification sound to be emitted from a sounding device (40) provided in an electric vehicle (200) in which at least part of driving force is produced by a motor to the outside of the electric vehicle (200), is provided with a behavior conversion processing section (21) that changes through time change processing an accelerator opening degree signal (11) among vehicle information signals (1) of the electric vehicle (200) so as to output a processed accelerator opening degree signal and with a notification sound signal generation processing section (3) that changes a pitch and a volume of a sound element signal outputted from a sound element (31, 310), based on the processed accelerator opening degree signal, so as to generate a notification sound signal.