In an automatic performing system, when the track is changed to one having a different loop bar number, the bar to be reproduced next is easily determined by first dividing the number of bars accumulated from the start of accompaniment by the loop bar number stored in the sequence track. Based on the remainder resulting from the division, the number of beats is determined and the present pointer is set. In the automatic performing system, by comparing the data at the next address with the part designation data, it is determined whether the read out data belongs to the designated part or not. Therefore, the accompaniment data corresponding to the designated part data can be read out and reproduced.