To perform tracking detection for a recording bit string with a simple probe structure by bringing the tips of a plurality of probes for independently detecting signals close to a plurality of bits located in the same bit string while making difference tracks and making comparison between the reproduction of information for the bit string and an independently detected reproducing signal.

The tips of two probes 108 and 109 attached to a cantilever tip are contacted with pits on a sample surface, and locally high-conductive regions 110 and 111 are formed on a lowconductive thin film 112. The probes 108 and 109 are contacted with the thin film 112 such that a straight line (n) connecting the contact surfaces of the tips of the probes makes an angle θwith a straight line (m) connecting the centers of the bits. In the case of scanning, the probe before a scanning direction reads the bits in the left side of a contact region in the scanning direction, and the probe after the same reads the bits in the right side of the contact region.