PURPOSE: To provide the manufacturing method of decorative floor covering material, with which floor of undiscernable joint can be produced efficiently at low cost and, at the same time, the robust decorative floor covering material strong in flexural load is obtained.

CONSTITUTION: A decorative material 1 is produced by arranging a plurality of decorative floor boards 2 so as to longitudinally stagger their longitudinal ends in succession. At the same time, base board materials are cut apart by stepwise cutting their midway position so as to correspond to the stepped shapes formed by the longitudinal end of the decorative material 1. After that, by joining the base board materials back to back under the condition that the stepped portions position outside so as to from a base board 5 having the same shape and size as those of the decorative material 1. Finally, the base board 5 is bonded to the rear surface of the decorative material 1 under the condition that projected parts 6 are formed by shifting the base board 5 longitudinally and the direction orthogonal to the longitudinal direction.