PURPOSE: To provide a GPS receiver for improving the accuracy for calculating position measurement at a location where the GPS receiver cannot be acquired easily.

CONSTITUTION: When only one GPS satellite can be acquired, a clock bias change rate prediction means 10 predicts the clock bias time change rate between the GPS satellite and self in this case based on the clock bias time change rate obtained by a multiple-satellite position measurement calculating means 4 when at least three GPS satellites are acquired, thus calculating the two-dimensional speed of the self by a few-satellite speed calculating means 11 based on the predicted clock bias time change rate.