We have used a Fabry-Perot type microcavity in porous silicon layered structures to enhance vibrational band intensities in infrared (IR) and Raman spectra. Parameters of the layers in the structure were chosen to have the cavity mode in the spectral region of adsorbate vibrational bands for the IR measurements and near a visible laser wavelength in the Raman experiment. In the IR spectra the enhancement achieved more than one order of magnitude due to photon confinement in the microcavity acting like a multipass cell. In the Raman experiment the enhancement factor of the band intensity was larger than 30. The obtained enhancement was due to the coupling of both laser radiation and Stokes photons of porous silicon with the cavity mode at optimal laser beam incidence and scattering angles.