Bi4Ti3O12 thin films have been grown on indium‐tin‐oxide coated glass by pulsed laser deposition. Films are rapidly thermal annealed at 650 °C in three kinds of atmospheres such as O2, N2, and air. The annealing atmosphere is found to be an important growth parameter which determines the crystallization, microstructures, and the leakage current behaviors. The film annealed in oxygen has a columnar grain structure with an amorphous phase, and its leakage current behavior is in agreement with the prediction of the space‐charge‐limited conduction model. The film annealed in nitrogen has polycrystalline porous structure, and its high field conduction is well explained by the thermoionic emission model, called the Poole–Frenkel emission. On the other hand, the film annealed in air has both the columnar and porous structures, and its electrical behavior shows characteristics of both models.