Errors of a measuring system are corrected by acquiring the phases of transmission tracking errors. A network analyzer includes a measuring system error factor recording unit which records measuring system error factors generated independently of frequency conversion carried out by a DUT, and an error factor acquiring unit which measures first coefficients and second coefficients of a correction mixer where a signal output from a terminal is a sum of a product of a signal input to the terminal and the first coefficient, and a product of a signal input to the other terminal and the second coefficient, and the ratio of magnitudes of the second coefficients is constant, and acquires the transmission tracking errors caused by the frequency conversion based on the measuring system error factors recorded in the measuring system error factor recording unit, the first coefficients, and the second coefficients.