The invention aims to implement a waveform display device capable of visibly displaying a comparison waveform in an arbitrary range and a waveform display method. The waveform display device for executing waveform display of waveform data on a display section comprises an input section for inputting at least two data ranges of the waveform data, and comparison waveform display means for executing waveform display of the waveform data while overlaid on one another on the display section based on at least two data ranges inputted by the input section.