  It is numerically demonstrated that effectively strong diamagnetic resonance
emerges at visible frequencies in stratified metal-dielectric metamaterials.
The effective optical constants are extracted by two-complex reflectivity
method. It is clarified that the effective diamagnetic response originates from
local diamagnetism at stratified thin metals. The effective diamagnetism is
crucially sensitive to the sturucture of unitcell. The effective diamagnetic
response is always associated with effective plasma frequency and is therefore
regarded as a magnetic component of the collective excitation.
