But Hwang Woo-suk, who is charged with fraud and embezzlement, repeated a claim that the fabrications were the work of junior researchers.
Dr Hwang, 53, is on trial after much-heralded research into human stem cells was found to be fake.
If convicted, he faces at least three years in prison.
Dr Hwang told the court about a 2005 paper published in the journal Science, in which his team claimed to have made stem cell lines from the skin cells of 11 different people.
A panel of experts at Seoul National University, where Dr Hwang used to work, has since dismissed the research as fake, and the paper has been retracted.
"I don't remember giving specific orders, but I admit I have overall responsibility," Dr Hwang said.
Fall from grace
Dr Hwang, formerly a professor at Seoul National University, had been viewed as a national hero for his apparently ground-breaking research on stem cells.
His findings appeared to bring researchers closer to the point where they could offer personalised cures, using tissue grown from embryonic stem cells to repair damaged organs or treat diseases like Alzheimer's.
But in December a panel at Seoul National University found that his research had been "intentionally fabricated". In May, prosecutors brought charges against him and his team.
He is accused of accepting donations worth 2bn won ($2.1m, £1.14m) on the basis of his research, and of embezzling a further 800m won ($831,000, £451,000) in research funds.
He is also alleged to have bought human eggs for his research work, which is a violation of South Korea's bio-ethics law.
He is being tried with five colleagues who are facing similar charges.
"Source":[ http://news.bbc.co.uk/2/hi/asia-pacific/5144082.stm]