We have discovered a new oxide phase which may be written as Ba3Cu3Ox IBCO). The sample was a thin film epitaxially grown on SrTiO3 (100) substrate. The BCO film was prepared using a pulsed ArF excimer laser ablation technique. X-ray analysis has revealed that the structure of the new phase, BCO, is tetragonal with the lattice parameters. a = 0.39 nm and c = 1.29 nm, with the unit cell consisting of a stack of three perovskite-type layers. During the film growth, the reflection high-energy electron diffraction (RHEED) pattern remained streaky and exhibited intensity oscillation as the film thickness increased. The RHEED oscillation periodicity was found to correspond to a single unit-cell-thick layer of BCO (1.29 nm). The BCO films do not show superconductivity but semiconductive behaviors.