A novel real-time signal analyzer which has the merits of both the conventional real-time FFT analyzer and a vector signal analyzer and eliminates the demerits of the analyzers. This analyzer is provided with an FFT processor (14) which performs FFT operation on time-domain data in real time, a FIFO memory (22) which delays the time-domain data before the FFT operation, and a double-port memory (24) which stores FFT-operated frequency-domain data from the processor (14) and, at the same time, delayed time-domain data read out from the memory (22). Since the delayed time by means of the memory (22) is set correspondingly to the operating time of the processor (14), the temporal correspondence relation between the delayed time-domain data and the frequency-domain data can be secured. Therefore, the time-domain data and the frequency-domain data having temporal simultaneousness and real-time properties can be obtained separately and simultaneously.