We have studied the structural and electrical properties of bismuth-modified lead zirconate titanate thin films. Specimens with various Bi contents, (Pb1-3/2xBix) (Zr0.52Ti0.48)O-3 (PBZT) thin films, were prepared on a Pt-coated Si wafer by the sol-gel method. Ferroelectricity confirmed by the measurement of dielectric constant and P-E hysteresis loop was found for specimens below x = 0.25, in which the values of both dielectric constant and remanent polarization were decreased with increasing Bi contents. The behaviors of the electrical properties with Bi content corresponded to the structural changes by increasing non-ferroelectric cubic phase with increasing Pi contents, which was thought to be due to the vacancies in Pb-sites created by the substitution of Bi into Pb.