[en] New shell-model Hamiltonians which can successfuly describe spin-dependent transition rates in nuclei are applied to study nuclear weak processes in stars. New v-induced reaction cross sections in "1"2C and "5"6Fe evaluated by the new Hamiltonians are shown to reproduce well the experimental data. Nucleosynthesis of light elements in supernova explosions (SNe) as well as v oscillation effects are discussed with the new cross sections. Electron capture and β-decay rates in stellar environments are re-evaluated in fp- and sd-shell nuclei. Nucleosynthesis in Type-Ia SNe, rp-process and X-ray burst are discussed with the new reaction rates in Ni isotopes. Important roles of accurate e-capture and β-decay rates in sd-shell nuclei on the cooling of stars with 8-10 solar masses by nuclear URCA processes and the fate of the stars are demonstrated. β-decay half-lives of waiting-point nuclei at N =126 are evaluated by shell- model calculations, and r-process nucleosynthesis up to Th and U region in both core-collapse SNe and binary neutron star mergers are studied. (paper)