(Proposal ID) S15A-058 (PI) Yabe, Kiyoto (Proposal Title) Chemical Abundance Ratio of Galaxies at z~1.4 Revealed with FMOS (Abstract) The chemical abundance is one of the important parameters for understanding galaxy evolution. In our previous FMOS observations, we measured the metallicity and the nitrogen-to-oxygen abundance ratio (N/O) from the stacked spectra of star-forming galaxies at z~1.4. We find the N/O is higher than that of local galaxies at a fixed metallicity. The high N/O can be explained by the effect of infalling pristine gas, which dilute metallicity keeping N/O higher. If the effect of gas infall is dominant, the morphology will be also affected by the drastic gas accretion; galaxies with higher N/O at fixed metallicity may show disturbed morphology. Our sample in the SXDS/UDS field whose metallicity, N/O, and morphology can be examined is, however, still very limited (~50). Here, we propose FMOS observations of galaxies in the COSMOS and the GOODS-N fields, where deep HST imaging data are available in the CANDELS fields. We aim to obtain a sample of ~ 300 galaxies in total, which is sufficient to detect, from stacked spectra, [N_ii]lambda6584 and [S_ii] lambda lambda6717,6731 lines necessary for the metallicity and N/O measurements. We explore the origin of high N/O in galaxies at high redshift, which would impose constrains not only galaxy evolution models but also fundamental stellar physics.