  We study how the multiplicity of the Fermi surface affects the zero-bias peak
in conductance spectra of tunneling spectroscopy. As case studies, we consider
models for organic superconductors $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ and
(TMTSF)$_2$ClO$_4$. We find that multiplicity of the Fermi surfaces can lead to
a splitting of the zero-bias conductance peak (ZBCP). We propose that the
presence/absence of the ZBCP splitting is used as a probe to distinguish the
pairing symmetry in $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$.
