This invention provides an HLA class I-expressing non-human animal that can be prepared efficiently in a simple manner within a short period of time, in which the transgene copy number to be introduced thereinto and the integration site of transgene are regulated, and in which the expression level of the transgene and the site of expression thereof are regulated. The invention also provides a method for preparing such non-human animal. In such HLA class I gene knock-in non-human animal, an artificial chimeric gene encoding an artificial chimeric protein comprising a protein composed of ²2 microglobulin, HLA class I ±1 and ±2 regions, and an MHC class I ±3 region of a non-human animal ligated in such order from the N terminus is expressed under the control of a transcription regulatory region of ²2 microglobulin gene of the non-human animal.
