To improve workability, secure water proof property and improve external appearance.

This panel member fitting structure is provided with plural supports erected at designated spaces, a surface panel member and a back panel member, and side edges of both surface and back panel members are supported and fitted on the supports to form a wall surface. The support 1 is provided with a recessed groove 7 continuously or intermittently formed in the longitudinal direction in a back side position in the side edge. The side edge of the back panel member 33 is fitted in the recessed groove 7, and the surface panel member 15 is provided with fixed pieces 20 projected on the side edges 15a, 15b. The fixed pieces 20 are fixed and fitted to the front end face 2 which is the surface side of the support 1. The fixed piece 20 is provided with a fixed part 21 fitted and fixed in the recessed part 17 of the back 16 of the surface panel member 15 and a shoulder part 27 extended from the fixed part 21, and the shoulder part 27 is projected from the side edges 15a, 15b of the surface panel member 15. The shoulder part 27 is fixed to the support 1.