To firmly fix a grid to furring strips without a trouble in surface processing even if the grid and the furring strips are welded.

This fitting structure of a grid is such that a substantially plate-like longitudinal grid 10, the front and rear of which are extended in the direction of depth is fitted between an upper furring strip 8 and a lower furring strip 9 arranged parallel to each other at a space between them. In this case, the opposite surfaces of the upper furring strip 8 and the lower furring strip 9 are provided with upper and lower welding pieces 20, 22 for welding the longitudinal grid 10 and upper and lower engagement pieces 21, 23 engaged with the longitudinal grid 10, and the longitudinal grid 10 is welded to both welding pieces 20, 22 at the rear end part in the direction of depth, and engaged with both engagement pieces 21, 23 for inhibiting vibration in the direction of width by a pair of engagement parts 10a, 10b separated from the rear end part in the direction of depth.