A positioning signal from a satellite positioning system is received at a mobile station, correction information from a reference station is used, a pseudo distance observation formula using a code and a phase distance observation formula using a carrier wave are used to perform positioning using single frequency at the mobile station, and these observation formulas are expressed by a satellite clock error, clock errors at the reference station and the mobile station, a ionospheric delay and a tropospheric delay, and a code bias and a phase bias of single frequency at the reference station, the mobile station and a satellite.