The problem of the present invention is to provide a method of efficiently producing therapeutic alternative corneal endothelial cells, particularly, a method capable of stably producing them in a condition suitable for intraocular transplantation (in the anterior chamber) in a large amount. Furthermore, the present invention aims to provide a composition for transplantation, which is preferable for intraocular administration, particularly, into the anterior chamber. A therapeutic alternative corneal endothelial cell sphere can be produced by culturing stem cells in suspension in a differentiation induction medium containing a GSK3 inhibitor, retinoic acid and a ROCK inhibitor. Addition of a viscoelastic substance during intraocular (into the anterior chamber) transplantation of the sphere or cultured corneal endothelial cells dispersed into single cells can increase the number of adherent cells after transplantation.