A head transport mechanism for reciprocating a carriage in a radial direction of a disc using a linear motor as a drive source is disclosed. In the head transport mechanism, cylindrical projections are formed on a support plate, threads are cut on the inner surfaces of the projections, and cutouts are formed in the distal ends of bottom yokes. The cutouts are brought into contact with the outer peripheral surfaces of the projections so as to locate the bottom yoke. In addition, protrusions protruding outward from superposed portions of the bottom yokes and top yokes in a longitudinal and/or lateral direction of the bottom yokes are formed in at least one end of each of the bottom yokes so that the top yokes can be assembled with the protrusions pressed when assembling the head transport mechanism.