In a satellite navigation system a navigation terminal continuously receives navigation signals from navigation satellites and continuously implements navigation calculations, thereby obtaining navigation calculation results, and executes in parallel: using clock offset values determined through the navigation calculations, calculates, in real time, changes in difference between time differences with regard to difference between time differences, which are differences between a clock offset value and a standard deviation value, which is the value of the standard deviation of fluctuation amounts of the clock offset values; determines, in real time, two navigation precision indices of the calculated navigation calculation results on the basis of each change in the calculated difference between time differences and standard deviation value; associates, in real time, the determined two navigation precision indices with the calculated navigation calculation results; and outputs, in real time, the navigation calculation results associated with the at least two navigation precision indices.