PURPOSE: To simply edit an interference state between adjacent waveforms from existing waveform data by successively shifting respective waveform data in a set range from both the end sides of the set range to the center.

CONSTITUTION: Waveforms stored in a waveform memory 20 are displayed as analog waveforms. An operator sets up a time direction range to be edited by an input device 36. The set range is displayed by two cursors. A microprocessor μP 32 finds out the addresses of the memory 20 which correspond to boundaries on both the sides of the set range. The μP 32 judges which is specified by the operator, extension or reduction in the set range, and in the case of extension, successively shifts the waveform data from the center of the set range to the outside. In the case of reduction, the μP 32 successively shifts the waveform data from the outside of the set range to the center. Consequently an interference state between adjacent waveforms can simply be edited from existing waveform data.