Disk tracking device

In a tracking device including a linear motor having a driving coil which is moved relative to a driving magnet extending over a predetermined range of movement of the driving coil in a longitudinal direction, a speed sensor having a detection coil which is moved relative to a detection magnet extending over said predetermined range of movement, a moving member having the driving coil fixed to one side thereof so that it can be reciprocated in the longitudinal direction over the predetermined range together with said driving coil upon application of a driving current thereto,

• the improvement wherein:
• said detection magnet is positioned in parallel with said driving magnet on the same one side of said moving member;
• and
• said speed sensor includes first and second coils mounted on respective opposite sides of the driving coil in said longitudinal direction on said same one side of said moving member and electrically connected to each other so as to cancel any induced voltage due to a magnetic field generated by proximity to said driving magnet, wherein at least one of said first and second coils functions as said detection coil.