Abstract: A volume reservation apparatus of an audio system stores data corresponding to currently-produced volume of sound and volume reservation data corresponding to the volume preprogrammed by a user for calculating a difference between the data at the time of wake-up reservation to supply a stepper-motor driving pulse corresponding to the difference, so that the preprogammed volume of sound is produced at the time of reservation. Also, a volume reservation method is provided, thereby solving the inherent problem of unsatisfactory wake-up indication effect resulting from the supply of recently-set low volume at a preprogrammed wake-up time when the wake-up time is preprogrammed under low volume state or a sleep-time function is preprogrammed under low volume state prior to preprogramming the wake-up time.