To scroll a waveform chart displayed on a monitor, in the same sense as pulling out or rewinding a piece of rolled waveform chart paper.

A waveform observation apparatus can switch between a horizontal display mode in which a time axis of a waveform chart is horizontally displayed and a vertical display mode in which the time axis is vertically displayed. The waveform observation apparatus comprises tracking scroll means and fast-forward scroll means that scroll the waveform chart on the basis of a touch operation. In the tracking scroll of a S107, a process that makes the waveform chart track and scroll according to movement of a fingertip F moving on the monitor 2 is executed. Once an operation is performed by flipping the fingertip F, the fast-forward scroll is executed in a S120 if a movement speed of the fingertip F is higher than a threshold, depending on a moved distance and a required time until a time point when the fingertip F comes free from the monitor 2.