Compositionally gradient (Ti1-xAlx)N coatings were deposited by the plasma enhanced chemical vapor deposition technique using a gas mixture of TiCl4, AlCl3, NH3, H-2, and Ar. The Al and the Ti concentrations in the coated layer changed linearly with the logarithms of the flow rate ratio Of AlCl3 to TiCl4, log(Q(AlCl3)/Q(TiCl4)) Since the vapor pressures of AlCl3 and TiCl4 change exponentially with the temperature within the range where the vaporizers of the source materials were heated for the deposition, the concentrations of Al and Ti in the coatings could be controlled simply by changing the temperatures of the vaporizers. X-ray diffraction (XRD) investigations showed that the compositionally gradient (Ti1-xAlx)N coating has the NaCl structure with a preferred orientation of (200), like TiN, up to the Al concentration of about X=0.8. The broadened XRD peak with its shifted position indicates that the lattice parameter of (Ti1-xAlx)N changed gradually with the concentration change in the coated layer. A suppressed growth of continuous columns and a tetragonally distorted lattice structure, which are supposed to come from the lattice parameter change during the film growth, could be observed in the cross-sectional transmission electron microscopy study.