Abstract: An arpeggiator scans key-pushing data and produces in sequence a plurality of playing data according to results of the scanning. The arpeggiator includes a rhythm pattern table having at least one step which stores therein a time interval of a rhythm, a sound generation continuing time and a sound generation strength coefficient. The arpeggio playing is performed according to the rhythm pattern table. The arpeggiator further includes a scan mode table having at least one step which stores one of a plurality of scan functions. The key-pushing data is scanned by sequentially referring to the stored scan function so as to produce playing data based on which the arpeggio playing is performed. The arpeggiator has a mode where the key-pushing data is erased based on key-releasing data and another mode where erasure of the key-pushing data is prohibited based on given hold data.