Embodiments in accordance with the present invention allow a resin member accommodating therein a trace, to have a small thickness. An HDD according to an embodiment of the present invention includes a resin accommodation member fixed to a side surface of arms. Part of a trace is accommodated in a slit formed in the accommodation member. Accommodating part of the trace in the slit helps suppress fluttering of the trace and improve head positioning accuracy. A corrugated surface structure is formed on each of surfaces of the arms and the accommodation member in abutment with each other. The corrugated surface structure is used to position the accommodation member in a pivot direction. The accommodation member, having the corrugated surface structure for positioning on the surface being fixed, can be made to have a thin wall.