A disk drive apparatus according to the present invention includes a horizontal guide mechanism and a vertical guide mechanism, which are disposed between a frame (10) and a slider (60) for slidably guiding the slider (60). The horizontal guide mechanism includes an engaging piece (69b) disposed in at least one of the frame (10) and the slider (60) and an engaging hole (24a), which is disposed in the other and is engaged with the engaging piece (69b). One of the frame (10) and the slider (60), in which the engaging piece (69b) is formed, is made of a metallic sheet material while the engaging piece (69b) is formed by bending part of the metallic sheet material. Forming the engaging piece (69b) by bending part of the metallic sheet material in such a manner simplifies the structure of the disk drive apparatus according to the present invention so that the fabrication is facilitated, enabling fabricating cost to be reduced.