Observational Study of the Galaxy Chemical Evolution through Optical and Far-infrared Emission Lines

Chemical properties of galaxies and their evolution during the cosmological timescale are useful to understand the galaxy evolution, since those are determined by the past star-formation history of galaxies with the gas inflow and outflow history. In the first half of my talk, first I will briefly review how the metallicity of galaxies is inferred from the observed spectra. Then I will show some results of metallicity measurements at various redshifts up to z~3, which are based on optical and near-infrared spectroscopic observations. In the second half of my talk, I will point out the limitations of optical and near-infrared observations in the metallicity studies. Then I will show some new far-infrared metallicity diagnostics and its actual applications to high-z galaxy using ALMA.