A communication test device can assist in identifying a cause of a change in throughput of a mobile communication terminal. The communication test device accumulates (a) trace data on a specific unit of data complying with a designated communication standard, and (b) throughput data on throughput of the specific unit of data transmitted to and received from a mobile communication terminal. Trace data and throughput data are extracted from the accumulation, and trace data is displayed. A graph of the variation of throughput with time is displayed on the display unit. Trace data corresponding to a time designated by an operating unit can also be displayed.