PURPOSE: To prevent the deformation of a cluster lid due to the change of external conditions by providing a concave-rail groove either on the opening end rim of the cluster lid or on the side of a meter unit for fitting one to the groove on the other to fix them with each other.

CONSTITUTION: An opening end rim 6a of a cluster lid 6 in an instrument panel 1 is provided with a concave-rail groove 6b with a U-shaped section, while a side 4b of a meter unit 4 is fitted into the groove 6b, with a U-shaped section, while a side part 4b of a meter unit 4 is fitted into the groove 6b, and fixed. This construction permits to prevent the opening end of the cluster lid 6 from changing in accordance with the elapse of time and the change of external conditions.