PURPOSE: To obtain a waveform generating circuit generating stably an optional wave by storing digitally an optional waveform in a write-only memory, reading it in a prescribed period and converting it by a digital/analog converter.

CONSTITUTION: A pulse signal outputted from a crystal oscillator 1 is outputted by a frequency division counter 2 as a 4-bit pulse train and a proper frequency is selected among frequency-division frequencies by a changeover switch 3, the frequency is frequency-divided by an 8-bit address counter 4 and fed to an ROM5 for waveform storage and an address signal is obtained. Thus, an adderss number is read sequentially out of a cell of the waveform storage ROM5 in the order of younger number. An instantaneous value of a digital quantity read sequentially by the address signal is convertered ito an analog signal by a D/A converter 6 and a desired waveform is obtained.