Core-collapse supernovae are violent explosion of massive stars at their end of life. The standard model of the supernova 
explosion is so-called ``delayed explosion scenario'', in which the neutrino heating plays an important role. In order to 
investigate whether this model works properly, we must solve raditation hydodynamic equations incorporating the neutrino 
radiative transfer with detailed
microphysics.

By performing axisymmetric hydrodynamic simulations of core-collapse supernovae with a spectral neutrino transport based on 
the isotropic diffusion source approximation scheme, we support the assumption that the neutrino-heating mechanism aided by 
the standing accretion shock instability and convection can initiate an explosion of 13 M_sun and 15 M_sun stars. In this poster, 
we show our recent works of multi-dimensional simulations.