A synthetic aperture radar signal processing device 10 includes a persistent scatterer extraction unit 11 which extracts, from time-series observation data related to an observation target observed from a plurality of observation directions by a radar, a plurality of persistent scatterers in respective observation directions; a persistent scatterer grouping unit 12 which groups the plurality of persistent scatterers in each of the observation directions; a group selection unit 13 which selects, in each of the observation directions, a persistent scatterer group that includes the persistent scatterers included in an analysis target from among groups generated by grouping; and a displacement speed processing unit 14 which synthesize displacement speeds of the selected persistent scatterer groups.