To provide a recording medium detection system which can precisely detect a recording medium.

When the recording medium is placed in a specified area 26, the recording medium can be precisely detected even when the recording medium is placed in any divided area which is made by dividing the specified area 26 into a plurality of areas, since any one of quantity, thickness, or length of magnetic wire is defined in such a way that magnetic flux density variation B1 found by a detecting section 52 based on a magnetizing reversal pulse detected at a set up position of a detection coil 54 is equal to or more than the magnetic flux density variation B2 as threshold to discriminate detection of the recording medium.