Herein disclosed a volume adjusting apparatus comprising: a plurality of sound inputting terminals for respectively inputting sound elements; a plurality of volume setting means respectively connected with the sound inputting terminals to respectively set volume levels of the sound elements inputted by the sound inputting terminals; and a plurality of sound outputting terminals for respectively outputting the sound elements at the volume levels respectively set by the volume setting means; and volume setting number counting means for counting the number of the active volume setting means; and timer interval calculating means for calculating the time interval on the basis of the number of the active volume setting means calculated by the volume setting number counting means, thereby optimizing the time interval on the basis of the number of the active volume setting means to provides a sufficient response time calculated on the basis of the number of the active volume setting means so that the volume setting means can respectively set the volume levels of the sound elements in accordance with the volume envelope values respectively generated by the volume envelope generating means at the time interval indicated by the timer means.