PURPOSE: To simplify the description of a control program by employing a first memory to which waveform data is transferred and a second memory to which attenuation quantity is transferred, and switching the attenuation quantity simultaneously with the switching of a waveform.

CONSTITUTION: Data in memories 2, 3 are read out with a waveform selection signal 11 from a CPU 1, and the output of the memory 2 is converted to an analog signal with a D/A converter 4, and is passed through a filter 5, and the amplitude of it is controlled with an attenuator 6. An arithmetic circuit 7 finds the sum of the attenuation quantity read out from the memory 3 with the waveform selection signal 11 from the CPU 1 and that of the attenuation quantity set with a waveform amplitude setting signal 12, respectively. Thereby, it is possible to set the attenuation quantity corresponding to the selection of the waveform at the attenuator 6, and to respond to a case where it is desired to change the amplitude of the waveform.