  Interference effect of neutron capture cross section between the compound and
direct processes is investigated. The compound process is calculated by
resonance parameters and the direct process by the potential mode. The
interference effect is tested for neutron-rich $^{82}$Ge and $^{134}$Sn nuclei
relevant to $r$-process and light nucleus $^{13}$C which is neutron poison in
the $s$-process and produces long-lived radioactive nucleus $^{14}$C
($T_{1/2}=5700$ y). The interference effects in those nuclei are significant
around resonances, and low energy region if $s$-wave neutron direct capture is
possible. Maxwellian averaged cross sections at $kT=30$ and $300$ keV are also
calculated, and the interference effect changes the Maxwellian averaged capture
cross section largely depending on resonance position.
