  The big bounce singularity of a simple 5D cosmological model is studied.
Contrary to the standard big bang space-time singularity, this big bounce
singularity is found to be an event horizon at which the scale factor and the
mass density of the universe are finite, while the pressure undergoes a sudden
transition from negative infinity to positive infinity. By using coordinate
transformation it is also shown that before the bounce the universe contracts
deflationary, and the universe has been existed, according to the proper-time,
for an infinitely long time.
