An electronic musical instrument employs a novel technique to produce a musical sound. A major part of a musical sound producing section of the electronic musical instrument is constructed by digital circuitry which is well adapted for an LSI fabrication. The electronic musical instrument comprises a volume control means to digitally perform a volume control to increase or decrease a performance volume, a period counting means to count one cycle of a musical sound wave by a plurality of counting steps in order to form a musical sound wave under digital control, a period control means to control the period counting means in accordance with the scale represented by a depressed performance key, and a means to instruct the rise and the fall of a musical sound wave by a value which is an integral multiple of a control value of the volume control means, for each block including a predetermined number of counting steps.