A wire rope flaw detector that is capable of accommodating a plurality of wire rope diameters and is inexpensive includes at least two magnetic sensor units that are integrated with a magnetizer and include planer coils placed opposite to each other with a magnetic circuit generated by the magnetizer in between, in the direction almost parallel to the magnetic circuit in a predetermined section of a wire rope. The detector further includes an adjuster capable of changing the distance between the at least two magnetic sensor units depending on the diameter of the wire rope.