A vibration detection system includes a seismic source device that generates a vibration wave repeated with a predetermined period, a vibration receiving device that receives a response wave due to the vibration wave transmitted via the ground, and a signal processing apparatus that processes measured vibration signals received by the vibration receiving device. The signal processing apparatus includes a separating part that separates individual periodic signals having a period according to a periodicity of the vibration wave generated by the seismic source from the measured vibration signals, the calculating part that calculates the standard periodic signal from the separated individual periodic signals, and the generating part that subtracts the standard periodic signal from the measured vibration signals and generates differential signals.