A correlation calculation process execution method utilizes a first mode and a second mode as a positioning mode that performs a correlation calculation process on a received signal of a positioning signal that is spread-modulated by a spreading code and a signal replica of the spreading code, the first mode being a mode in which correlation values are averaged in a first mode process period to output a correlation value, and the second mode being a mode in which correlation values are integrated in a second mode process period to output a correlation value, the method including repeating the first mode and the second mode while setting an intermediate time of the first mode process period to be the same as an integration reference time of the second mode process period, and variably setting a ratio of an ON/OFF period in at least one period of the first mode process period and the second mode process period.