To realize a GNSS receiver that can perform further optimal correlation processing on a positioning signal phase-modulated by a CBOC signal. A correlation processing module 32 performs correlation processing between a baseband signal and a BOC(1, 1) replica code to output a BOC(1, 1) correlation data, and also performs correlation processing between the baseband signal and a BOC(6, 1) replica code to output a BOC(6, 1) correlation data. A synthesis module 33 uses a BOC(1, 1) synthesizing ratio coefficient G11 and a BOC(6, 1) synthesizing ratio coefficient G61 to synthesize the BOC(1, 1) correlation data with the BOC(6, 1) correlation data, and outputs the synthesized correlation data to a calculation module 30. The calculation module 30 detects a reception environment based on the synthesized correlation data, sets a BOC(1, 1) synthesizing ratio coefficient and a BOC(6, 1) synthesizing ratio coefficient based on the reception environment, and supplies them to the synthesis module 33.