Provided is an exhaust gas cleaning catalyst capable of inhibiting the grain growth of particulates. An exhaust gas cleaning catalyst of the present invention includes composite metal particulates containing Pd and Rh, where the average proportion of the total number of Rh atoms relative to the total number of Pd and Rh atoms is 0.5 atom%, and given an X-ray wavelength of 1.5403 Å, when XRD analysis is carried out under the condition that the diffraction surface is the crystal lattice face of the Pd(111), and diffraction angles 2θ indicating the positions of the diffraction peaks on the diffraction surface are identified, the absolute value of the difference between the theoretical lattice constant B calculated from a formula related to Vegard's law using the identified values, and the actual lattice constant C calculated from a formula related to lattice constants and Bragg's law does not exceed 1.020×10 -3 (Å). A smaller absolute value of the difference between the theoretical lattice constant B and the actual lattice constant C is associated with a higher degree to which the Pd and Rh are combined with one another.