A method of searching a Global Navigation Satellite System, GNSS, signal to determine whether a target signal has been captured successfully, the method comprising the steps of: generating a plurality of replicas of the target signal, the replicas being generated at a plurality of frequencies, respectively, that are set at frequency intervals in a group, wherein the frequency intervals are determined based on the period of a diffusion code used to modulate the target signal; correlating a reception signal with each of the plurality of replicas to produce a plurality of correlation values for the group; and determining whether the target signal is successfully captured, based on the plurality of correlation values in the group, characterized in that the step of determining whether the target signal is successfully captured includes: detecting a highest correlation value for every frequency in the group; setting the highest correlation values to be peak correlation values of the frequencies, respectively; detecting a highest peak value that is a highest value among the peak correlation values of the respective frequencies; determining a highest noise value among the peak correlation values of the respective frequencies other than the highest peak value; and calculating a ratio between the highest peak value and the highest noise value; wherein whether the target signal is successfully captured is determined based on the ratio, and when it is determined that the target signal is not successfully captured by the step of determining whether the target signal is successfully captured, the plurality of frequencies are shifted by a fixed frequency width shorter than the frequency interval. generating a plurality of replicas of the target signal, the replicas being generated at a plurality of frequencies, respectively, that are set at frequency intervals in a group, wherein the frequency intervals are determined based on the period of a diffusion code used to modulate the target signal; correlating a reception signal with each of the plurality of replicas to produce a plurality of correlation values for the group; and determining whether the target signal is successfully captured, based on the plurality of correlation values in the group, characterized in that the step of determining whether the target signal is successfully captured includes: detecting a highest correlation value for every frequency in the group; setting the highest correlation values to be peak correlation values of the frequencies, respectively; detecting a highest peak value that is a highest value among the peak correlation values of the respective frequencies; determining a highest noise value among the peak correlation values of the respective frequencies other than the highest peak value; and calculating a ratio between the highest peak value and the highest noise value; detecting a highest correlation value for every frequency in the group; setting the highest correlation values to be peak correlation values of the frequencies, respectively; detecting a highest peak value that is a highest value among the peak correlation values of the respective frequencies; determining a highest noise value among the peak correlation values of the respective frequencies other than the highest peak value; and calculating a ratio between the highest peak value and the highest noise value; wherein whether the target signal is successfully captured is determined based on the ratio, and when it is determined that the target signal is not successfully captured by the step of determining whether the target signal is successfully captured, the plurality of frequencies are shifted by a fixed frequency width shorter than the frequency interval.