A method for preparing neoplastically transformed cells from human-derived cells, including the step of introducing human telomerase catalytic subunit (hTERT) gene, SV40 small T antigen (SV40ST) gene, and an antisense oligonucleotide derived from human 28S rRNA into the human-derived cells. The method for preparing neoplastically transformed cells from human-derived cells can be utilized when a variety of human normal cells are induced to be neoplastically transformed in order to elucidate cancer onset mechanisms, so that the method can be effectively utilized in search of target molecules for a new medicament.