A lamp device comprises a lamp seat, having a body; a heat installed at an upper end of the body for electrically connecting to an external power source; an electric joint extending from the head; and a connecting shaft extending downwards; and a heat dissipation assembly including: a heat dissipating mask having an axial hole; the connecting shaft passing through the axial hole so that the heat dissipating mask is connected to the body; and the heat dissipating mask is rotatable; a conductive unit installed at an upper side of the heat dissipating mask; the conductive unit being electrically connected to the electric joint even the heat dissipating mask rotates with respect to the body; and a lamp set driven electrically and installed at a lower side of the heat dissipating mask; and the lamp set being retained to the conductive unit through the heat dissipating mask.