A metal enhanced emission of more than 20-fold is observed from a Langmuir-Blodgett (LB) monolayer on a planar aluminum layer with a polymer spacer. The spectral change of the metal enhanced emission using the metal layer is discussed experimentally and theoretically. Finite-difference time-domain simulations and transfer matrix calculations have been performed to investigate the cause of the enhancement. The analytical solution of the enhancement factor of the interference enhancement is also derived assuming the planar aluminum layer as a perfect electric conductor. Furthermore, we have demonstrated control of emission color of the LB film from the yellow-green to blue or red using the metal enhanced emission.