  Using known relation between $SU(2,2|4)$ supertwistors and $SU(2)$ bosonic
and fermionic oscillators we identify the physical states of quantized massless
$AdS_5\times S^5$ superparticle in supertwistor formulation and discuss how
they fit into the spectrum of fluctuations of IIB supergravity on $AdS_5\times
S^5$ superbackground.
