1. A method of positioning by calculating a position or a speed of a GNSS receiving apparatus by using a track filter based on reception signals of GNSS positioning signals, comprising: detecting multipath based on a position accuracy degradation serving as an index of a positioning accuracy based on locations of GNSS satellites and a C/No; setting an error covariance matrix of observed errors serving as a parameter of designing the track filter, based on whether the multipath is detected; and calculating the position or the speed by using the track filter set in the setting the error covariance matrix.