A hinge unit comprising: a hinge base having two wings and a housing connected between the two wings; a hinge arm pivotably connected to the hinge base and having two side walls and a bottom wall connected between the two side walls, each side wall having a first connection hole and a second connection hole, the two side walls and the bottom wall defining a room; a securing frame having two side panels and an engaging member connected between the two side panels, each of the two side panels having a first connection portion, a second connection portion and an engaging portion, the first connection portion engaged with the first connection hole of the hinge arm, the second connection portion located corresponding to the second connection hole of the hinge arm, the engaging portion located on an inside of the side panels corresponding thereto and being adjacent to the second connection portion, the engaging member having a through hole and a protrusion extending from a periphery of the through hole; a fixing member extending through the second connection hole of the hinge arm and the second connection portion of the securing frame so as to connect the securing frame to the hinge arm, and a damper having a body and a piston, the body having a front end portion and a rear end portion, the rear end portion having a contact portion, the piston being axially movable relative to the body of the damper, the damper connected between the two side panels of the securing frame, the piston extending through the through hole of the engaging member, the contact portion of the body contacting the engaging portion of the side panels, characterized in that the front end portion has a recessed area) and the protrusion of the engaging member engages with the recessed area of the body of the damper, and in that the engaging member of the securing frame has an opening which communicates with the through hole and the protrusion extends toward the engaging portion. a hinge base having two wings and a housing connected between the two wings; a hinge arm pivotably connected to the hinge base and having two side walls and a bottom wall connected between the two side walls, each side wall having a first connection hole and a second connection hole, the two side walls and the bottom wall defining a room; a securing frame having two side panels and an engaging member connected between the two side panels, each of the two side panels having a first connection portion, a second connection portion and an engaging portion, the first connection portion engaged with the first connection hole of the hinge arm, the second connection portion located corresponding to the second connection hole of the hinge arm, the engaging portion located on an inside of the side panels corresponding thereto and being adjacent to the second connection portion, the engaging member having a through hole and a protrusion extending from a periphery of the through hole; a fixing member extending through the second connection hole of the hinge arm and the second connection portion of the securing frame so as to connect the securing frame to the hinge arm, and a damper having a body and a piston, the body having a front end portion and a rear end portion, the rear end portion having a contact portion, the piston being axially movable relative to the body of the damper, the damper connected between the two side panels of the securing frame, the piston extending through the through hole of the engaging member, the contact portion of the body contacting the engaging portion of the side panels, characterized in that the front end portion has a recessed area) and the protrusion of the engaging member engages with the recessed area of the body of the damper, and in that the engaging member of the securing frame has an opening which communicates with the through hole and the protrusion extends toward the engaging portion.