Disclosed are a hinge unit which couples a first member and a second member, the hinge unit including: a conic shaft which is coupled to the first member, and comprises a hinge pivot, a conic unit of a truncated cone shape, the radius of which is extended in an end area of the hinge pivot, and a first rocking unit formed to an outer surface of the conic unit; and a conic sleeve which is coupled to the second member, and comprises a sleeve main body formed with a conic accommodating unit having a shape corresponding to the conic unit in an inner part of the conic accommodating unit, and a second rocking unit formed to an inner surface of the conic accommodating unit to be coupled with the first rocking unit.