Zodiacal light is sunlight scattered by interplanetary dust and has 
been an important observational target for understanding the evolution 
of our solar system. In order to study the origin and structure of this 
dust, we reanalyze the Imaging Photo Polarimeter (IPP) data onboard 
Pioneer 10 and 11, which were launched in 1972 and 1973, respectively. 
We apply a new method developed by Matsuoka et al. 
to subtract integrated star light (ISL) and diffuse galactic light 
(DGL). We find that the spatial distribution of observed zodiacal light, 
whose heliocentric distances (R) are smaller than 2AU, is consistent 
with the Kelsall et al. J-band zodiacal light model.  We also find that 
the mean zodiacal light brightness whose solar elongation angles are 
larger than 120���, sharply drops to zero at R~2.7AU and continues to the 
Jovian orbit. This result revises previous report on the detection of 
zodiacal light in the asteroid belt by Hanner et al. Furthermore, we 
detect a small enhancement of the brightness towards the anti-solar 
direction, which indicates the existence of the dust belt beyond 
Jupiter. These findings support that the main source of the 
interplanetary dust in the vicinity of the Earth orbit is not from the 
steroids but from the comets.