A spectrum analyzer includes: two sets of measuring units having mixers, local oscillators, and IF sections for separately measuring frequency characteristics of two input signals; a trigger control section which generates a trigger signal for specifying a measurement start timing in each of the two sets of measuring units; a sweep control section which simultaneously sends an instruction to the two local oscillators when a trigger signal is inputted and performs a sweep control so that the two local oscillators output local oscillation signals of the same frequency at the same timing. This provides a frequency characteristics measuring device which can simplify the configuration for performing a measurement and reduce the undue effort required for the measurement.