PURPOSE: To manufacture three sorts of luminaires with different wattage at a low cost, and to secure the mechanical strength, by providing lid structures to close the openings of the cases, as well as combining two sorts of lamp holding cases.

CONSTITUTION: Two sorts of lamp holder cases smaller than the conventional lamp holding case, including the first lamp holder case 3 having an installing part to a luminaire main body and a socket 2, and the second lamp holder case 5 having a socket 4, are combined. As a result, since three sorts of luminaires including a 62W type, a 727W type, and 102W type can be manufactured, the manufacturing cost can be reduced by reducing the number of parts and making the size small. In either combinating condition of the first, the second, and the third luminaires, the first, the second, and the third lid bodies function as the connecting element of the lamp holder cases each other, and the mechanical strength of the whole body of the connected holder cases can be secured sufficiently while composing by dividing the holder case into two small parts, consequently.