Most of them are really interested in Thailand, but they're a bit concerned since most have never invested abroad before," Mr Iwasaki said.
Saitama prefecture is just north of Tokyo and the site of several Japanese car makers including Honda.
Mr Iwasaki said the 30 companies investing in Thailand already are mostly subcontractors producing auto parts for major Japanese car makers including Honda, Toyota and Nissan.
To attract more Japanese investors here, the two sides will cooperate in launching business support desks to help facilitate investment.