  The superconductivity precursor phenomena in high temperature cuprate
superconductors was studied by direct measurements of superconducting
condensate with the use of the $c$-axis optical conductivity of
YBa$_{2}$(Cu$_{1-x}$Zn$_{x}$)$_{3}$O$_{y}$ for several doping levels ($p$) as
well as for several Zn-concentrations. Both of the real and imaginary part of
the optical conductivity clearly showed that the superconducting carriers
persist up to the high temperatures $T$$_{p}$ that is higher than the critical
temperature $T$$_{c}$ but lower than the pseudogap temperature $T$$^{\ast}$.
$T$$_{p}$ increases with reducing doping level like $T$$^{\ast}$, but decreases
with Zn-substitution unlike $T$$^{\ast}$.
