A rail inspection system , comprising: a first sensor unit which is disposed to face a rail for a vehicle, and includes at least one receiver coil (6, 6-1) and at least one oscillation coil which are arranged in an arrangement direction intersecting with a layout direction of the rail ; wherein the layout direction is a front and rear direction of the rail and the arrangement direction is a direction perpendicular to the layout direction; an AC voltage source; and a displacement detection unit which is configured to detect a displacement between the rail and the first sensor unit based on an induced voltage of the receiver coil (6, 6-1), characterized in that the first sensor unit includes a first oscillation coil (5A-1), a first receiver coil (6-1), and a second oscillation coil (5B-1) which are arranged along the arrangement direction, and the AC voltage source is configured to apply the AC voltage to the first oscillation coil (5A-1) and the second oscillation coil (5B-1) having a reverse phase, such that reverse magnetic fields are generated from the first oscillation coil (5A-1) and the second oscillation coil (5B-1), wherein the first oscillation coil (5A-1) and the second oscillation coil (5B-1) are connected in series and the AC voltage source is configured to apply the AC voltage to a series circuit comprising the first oscillation coil (5A-1) and the second oscillation coil (5B-1), and wherein the first oscillation coil (5A-1) and the second oscillation coil (5B-1) are disposed at an equal interval in a left and right direction of the receiver coil , such that, when the displacement is a first displacement, to generate a detection signal, in which a voltage with a first maximum value is induced, and when the displacement is a second displacement, to generate a detection signal in which a second maximum value of which a phase is reversed against the first maximum value is induced. a first sensor unit which is disposed to face a rail for a vehicle, and includes at least one receiver coil (6, 6-1) and at least one oscillation coil which are arranged in an arrangement direction intersecting with a layout direction of the rail ; wherein the layout direction is a front and rear direction of the rail and the arrangement direction is a direction perpendicular to the layout direction; an AC voltage source; and a displacement detection unit which is configured to detect a displacement between the rail and the first sensor unit based on an induced voltage of the receiver coil (6, 6-1), the first sensor unit includes a first oscillation coil (5A-1), a first receiver coil (6-1), and a second oscillation coil (5B-1) which are arranged along the arrangement direction, and the AC voltage source is configured to apply the AC voltage to the first oscillation coil (5A-1) and the second oscillation coil (5B-1) having a reverse phase, such that reverse magnetic fields are generated from the first oscillation coil (5A-1) and the second oscillation coil (5B-1), wherein the first oscillation coil (5A-1) and the second oscillation coil (5B-1) are connected in series and the AC voltage source is configured to apply the AC voltage to a series circuit comprising the first oscillation coil (5A-1) and the second oscillation coil (5B-1), and wherein the first oscillation coil (5A-1) and the second oscillation coil (5B-1) are disposed at an equal interval in a left and right direction of the receiver coil , such that, when the displacement is a first displacement, to generate a detection signal, in which a voltage with a first maximum value is induced, and when the displacement is a second displacement, to generate a detection signal in which a second maximum value of which a phase is reversed against the first maximum value is induced. <EOS>