A head suspension assembly includes a plate member located at a position distanced from the base. A head slider is supported at the front end of the plate member. A leaf spring connects the rear end of the plate member to the front end of the base. A rib extends at least from the rear end of the plate member toward the front end of the plate member. A restraining piece is located in a space between the rib and the base. When the internal force is induced in the head suspension assembly in response to an impact, the leaf spring receives a force to bend upward to move the head slider upward. The restraining piece serves to avoid any change in the position of the plate member relative to the base. The lead spring is prevented from bending. The plate member is thus reliably prevented from an upward movement.