Abstract: A mattress for human resting which is modular and is composed of parts made of different materials, determining a mattress density that is diversifiable according to individual requirements. The mattress is composed of a first structural part, constituting a containment element in which one or more longitudinal receptacles are formed. A second additional part is removably accommodatable in the one or more receptacles and is constituted by a mat made of synthetic or natural material determining overall variation in density or in selected points of the resting surface.