  Superkamiokande atmospheric neutrino data (contained and upward going through
$\mu$ events) for 990 days are analyzed in the framework of four neutrinos
(three active and one sterile neutrinos) without imposing constraints of Big
Bang Nucleosynthesis. It is shown that the wide range of the oscillation
parameters is allowed at 90% confidence level ($0.1\lesssim
|U_{s1}|^2+|U_{s2}|^2\le 1$), where the best fit point has some contribution of
$\nu_\mu\leftrightarrow\nu_s$ and contribution of $\Delta m^2_{\rm\scriptsize
LSND}$. The case of pure $\nu_\mu\leftrightarrow\nu_s$ oscillation is excluded
at 99.7%CL (3.0$\sigma$) which is consistent with the recent analysis by the
Superkamiokande group. Combining this result with the analysis by Giunti,
Gonzarez-Garcia and Pe\~na-Garay, it is found that the Large Mixing Angle and
Vacuum Oscillation solutions of the solar neutrino problem are also allowed.
