Abstract. We present sets of equation of state (EOS) of nuclear matter including hyperons using an SU_f(3) extended relativistic mean field (RMF) model with a wide coverage of density, temperature and charge fraction for numerical simulations of core-collapse supernovae. Coupling constants of Σ and Ξ hyperons with the σ meson are determined to fit the hyperon potential depths in nuclear matter, U_Σ(ρ₀) +30 MeV and U_Ξ(ρ₀) −15 MeV, which are suggested from recent analyses of hyperon production reactions. At low densities, the EOS of uniform matter is connected with the EOS by Shen et al, in which the formation of finite nuclei is included in the Thomas–Fermi approximation. In the present EOS, the maximum mass of neutron stars decreases from 2.17 M (Neμ) to 1.63 M (NYeμ) when hyperons are included. In a spherical, adiabatic collapse of a 15 M star by the hydrodynamics without neutrino transfer, hyperon effects are found to be small, since the temperature and density do not reach the region of hyperon mixture, where the hyperon fraction is above 1 % (T > 40 MeV or ρ_B > 0.4 fm⁻³).