The contracted Gaussian-type function (CGTF) sets by Huzinaga and co-workers are improved by an extensive optimization of exponents and contraction coefficients for the first-row atoms Li to Ne. The largest improvements in the total energy are 1.043, 0.096, 0.122, 0.23, 0.24, and 0.36 mhartrees, respectively, for the (33/3), (43/4), (53/5), (64/5), (64/6), and (74/7) sets. The virial ratios are considerably improved by the present optimization. The change in exponents and contraction coefficients amounts to 19%. Splitting the valence part of the CGTFs and adding polarization functions, we have examined the effect of the polarization functions on the properties of N-2 molecule in self-consistent-held (SCF) and configuration interaction (CI) calculations, Referring to the results of a very large basis set, we confirmed that both in the SCF and CI calculations, polarization functions added to the present CGTF sets almost work as pure polarization functions; no basis set superposition error was found both in the SCF and CI calculations except for (321/21) and its family derived from (33/3) set in the SCF calculations.