PURPOSE: To execute a fixation with a proper movement according to the kinds and number of cabinets, to facilitate a work and to prevent the appearance from being spoiled after fitting in the fixation of the top board and cabinet by fitting the top-board-side fitting movably on the undersurface of the top board and housing the fitting within the top board.

CONSTITUTION: A fitting far 4 of a fittings 5 of a work top 1 is fitted in the front and rear of the top board lower surface, a recessed part 7 of the fittings 5 is hooked to a projecting part 6, and by providing a gap 8 with the lower surface of the work top, the fittings 5 is movably fitted. To an L-shaped part 9 of the fittings 5, a screw hole 10 is provided, and simultaneously, the L-shaped part 9 is made to be within the outer dimension of the work top 1. In a front far 12 of a cabinet 11 and the cabinet of a rear plate 14, a fixings 18 opposed to the fittings 5 of the work top 1 is fixingly fitted. First, the cabinets 11 are mutually fixed, next, the fittings 5 of the work top 1 is matched to the position of the fixings 18 fixingly fitted to the front far 12 and rear plate 14 of the cabinet 11, it is placed on the cabinet 11, the fittings 5 is moved from the inside, and it is fixed with the fixings 18 and a screw 19.