  The axino with mass in the GeV region can be cold dark matter(CDM) in the
galactic halo. However, if R-parity is broken, for example by the bilinear
terms $\mu_\alpha$, then axino($\tilde a$) can decay to $\nu+\gamma$. In this
case, the most stringent bound on the axino lifetime comes from the diffuse
photon background and we obtain that the axino lifetime should be greater than
$3.9\times 10^{24}\Omega_{\tilde a}h$ s which amounts to a very small bilinear
R-parity violation, i.e. $\mu_\alpha<1$ keV. This invalidates the atmospheric
neutrino mass generation through bilinear R-violating terms within the context
of axino CDM.
