Embodiments of the present invention provide a portable rotary disk type storage device provided with a form factor allowing dimensions of an accommodation space in a longitudinal and a lateral direction to be reduced. In one embodiment, the storage device has a head disk assembly provided with a rotary disk recording medium and a casing accommodating the rotary disk recording medium and forming a totally closed space. The device further has a PCB provided with a connection pad disposed substantially parallel with a recording surface of the rotary disk recording medium and connectable to a host system connector and a control circuit for the head disk assembly and connected to the head disk assembly with an FCP and mechanically released therefrom. Housings accommodating the head disk assembly and the PCB and having an opening portion in alignment with the connection pad are provided.