Provided are a non-contact sensor (10) and an inspection method that uses the non-contact sensor (10), the non-contact sensor (10) being configured such that a magnetic circuit is constituted by an excitation coil (13), a first detection coil (11) and a second detection coil (12), and the first detection coil (11) and the second detection coil (12) are formed so as to be symmetrical with each other in terms of the magnetic circuit. An inspection device (20) comprises: a first input unit (21) to which a signal is input from the first detection coil (11); a second input unit (22) to which a signal is input from the second detection coil (12); a difference calculating unit (23) that calculates a difference between a first signal from the first input unit (21) and a second signal from the second input unit (22); a signal processing unit (24) that processes a difference signal calculated by the difference calculating unit (23); and an oscillation unit (25) that generates an excitation signal for the excitation coi
