Disclosed is a novel means for making it possible to steadily mass-producing a knock-out individual even of a large animal. A method according to the present invention is a method for producing a non-human large mammal or fish (a non-human animal) each capable of producing a gamete originated from a different individual. The method comprises: transplanting at least one pluripotent cell originated from a second non-human animal into a cleavage stage embryo that is originated from a first non-human animal and has genome in which the function of nanos3 gene is inhibited, thereby preparing a chimeric embryo and developing the chimeric embryo, thereby producing an individual. When a pluripotent cell having genome in which a desired gene is knocked out is used as the pluripotent cell originated from the second non-human animal, it becomes possible to allow the first non-human animal to produce a germ cell in which the desired gene is knocked out. By crossing non-human animals which are produced in the above-mentioned manner with each other, a knock-out non-human animal can be mass-produced easily.La présente invention concerne un nouveau moyen pour rendre possible la production en masse de manière stable dun individu "knock-out", même un animal de grande taille. Un procédé selon la présente invention est un procédé de production dun mammifère ou dun poisson non humain (un animal non humain) de grande taille, apte chacun à produire un gamète provenant dun individu différent. Le procédé comprend : la transplantation dau moins une cellule pluripotente provenant dun second animal non humain dans un embryon au stade de clivage qui est issu dun premier animal non humain et a génome dans lequel la fonction du gène nanos3 est inhibée, ce qui permet de préparer un embryon chimérique et le développement de lembryon chimérique, ce qui permet de produire un individu. Lorsquune cellule pluripotente ayant un génome dans lequel un gène souhaité est inactivé est utilisée en tant que cel
