A signal processing apparatus includes a memory, and a processor coupled to the memory and configured to perform a process including obtaining measurement data including a signal of interest and an interference signal generated in proximity to a signal source of the signal of interest, estimating a signal source in an extraction target area including the signal source of the signal of interest and a signal source of the interference signal based on the measurement data, selecting the signal source of the interference signal based on a result of the estimating a signal source and extracting interference signal data generated from the selected signal source of the interference signal, and extracting the signal of interest by removing a common part between the measurement data and the interference signal data.