The present application relates to a technique for reducing the circuit scale of a testing device having a function of performing a fading process with respect to a propagation channel of S×U channels assumed between transmitting and receiving antennas, using a terminal compatible with MIMO for transmitting a downlink signal from a base station to a mobile terminal with the number of base station-side antennas S and the number of terminal-side antennas U, or a circuit substrate, an integrated circuit and the like built into the terminal, as a test object. The multiplication arithmetic operation of the characteristics of the propagation channel and the modulation signal is performed in the frequency domain, and a time domain signal is generated from the arithmetic operation result. It's possible to considerably reduce the scale of a circuit that performs inverse Fourier transform and the scale of a circuit that generates propagation channel characteristics.