The company's EVP and chief financial officer Masaru Kato told a conference call today that work on the system is "already underway".
He revealed that production resource was factored into costs for the company's full year financial results, which were released yesterday.
"For the home equipment the PS3 still has a product life," he said.
"But this is a platform business, so for the future platform - when we'll be introducing what product, I cannot discuss - but our development work is already under way, so the costs are incurred there."
The head of Sony's global games development team, Shuhei Yoshida, said last year that the firm expects Microsoft and Nintendo to launch their next-gen home systems before the new PlayStation arrives on the market.
"Naturally, in my opinion, Microsoft will make the first move," he said. "Or, because Nintendo's approach was not to upgrade much on its basic hardware - Wii doesn't even support HD resolution - so they might be the first to move.