PURPOSE: To prevent position deflection of an auxiliary base forward and back, and eliminate possibility of deformation or discoloration even when it is installed on a work top having a step and comprising artificial marble or the like of low heat-resistant temperature.

CONSTITUTION: An auxiliary base 5 or 6 is provided with overhang parts 5b, 6b protruded toward a gas range 4 at lower parts of both the front and back ends in the depth direction of a leg part 5a or 6a at a part positioned on the gas range 4 side, and the auxiliary base 5 or 6 is installed in such a way that both overhang parts 5b, 6b hold end parts of front and back side surfaces of a range plate 4a in the gas range 4.