  We study optical radiation of aspherical supernovae (SNe) and present an
approach to verify the asphericity of SNe with optical observations of
extragalactic SNe. For this purpose, we have developed a multi-dimensional
Monte-Carlo radiative transfer code, SAMURAI (SupernovA MUlti-dimensional
RAdIative transfer code). The code can compute the optical light curve and
spectra both at early phases (<~ 40 days after the explosion) and late phases
(~ 1 year after the explosion), based on hydrodynamic and nucleosynthetic
models. We show that all the optical observations of SN 1998bw (associated with
GRB 980425) are consistent with polar-viewed radiation of the aspherical
explosion model with kinetic energy 20 x 10^{51} ergs. Properties of off-axis
hypernovae are also discussed briefly.
