The object is to provide a method for introducing a gene into an embryo for the purposeof producing a human disease model primate animal by using a non-human primateanimal such as a marmoset.Disclosed is a method for introducing a foreign geneinto an early embryo of a non-human primate animal, which comprises the stepsof: placing the early embryo of the non-human primate animal in a 0.2-0.3 M sucrosesolution to increase the volume of a perivitelline space of the early embryoand injecting a viral vector carrying a human foreign gene operably linked toa promoter into the perivitelline space of the early embryo.