  We gave an extensive study for the quasi-periodic perturbations on the time
profiles of the line of sight (LOS) magnetic field in 10x10 sub-areas in a
solar plage region (corresponds to a facula on the photosphere). The
perturbations are found to be associated with enhancement of He I 10830 A
absorption in a moss region, which is connected to loops with million-degree
plasma. FFT analysis to the perturbations gives a kind of spectrum similar to
that of Doppler velocity: a number of discrete periods around 5 minutes. The
amplitudes of the magnetic perturbations are found to be proportional to
magnetic field strength over these sub-areas. In addition, magnetic
perturbations lag behind a quarter of cycle in phase with respect to the p-mode
Doppler velocity. We show that the relationships can be well explained with an
MHD solution for the magneto-acoustic oscillations in high-\b{eta} plasma.
Observational analysis also shows that, for the two regions with the stronger
and weaker magnetic field, the perturbations are always anti-phased. All
findings show that the magnetic perturbations are actually magneto-acoustic
oscillations on the solar surface, the photosphere, powered by p-mode
oscillations. The findings may provide a new diagnostic tool for exploring the
relationship between magneto-acoustic oscillations and the heating of solar
upper atmosphere, as well as their role in helioseismology.
