Signals output from two filters included in a filter section 70 and differing in passband are respectively stored in different memories included in a memory section 80, and a positioning process is performed based on the signal stored in the memory. Specifically, the signal strength of a received signal is calculated by a coherent accumulation process and an incoherent accumulation process, and a signal system used for positioning is alternatively switched to a high-sensitivity system S1 or a high-accuracy system S2 as a result of determining whether or not the signal strength is equal to or greater than a threshold value.