Two South Australian races will offer $1 million in prize money in May.

Racing Minister Leon Bignell says the SA government is investing $6 million over two years in more prize money and marketing for the state's autumn carnival.

The boost means the Goodwood and the Robert Sangster Stakes will each offer a million dollars in prize money and the SA Derby's purse will rise to $600,000.

Prize money will also go up for another 14 races, with each to offer at least $100,000.

Bignell says the higher stakes will improve the profile of the racing industry in SA, which is the only mainland state currently lacking a $1 million race.

"The establishment of two $1 million races will undoubtedly provide the catalyst for a greater interstate and international focus on Adelaide," Bignell said in statement on Friday.

"There is a deep and rich tradition of racing in South Australia and we want to ensure we stay on top of the game."

He said May was the best time for SA to take "centre stage" in Australian racing and he expected the carnival would now attract more interstate and global tourists.

Thoroughbred Racing SA chair Frances Nelson QC said the autumn carnival had been growing over the past three years and the higher prize money would help it along further.

"This increase in prize money not only provides that critical impetus for attracting bigger and better fields, but it's also another important step for South Australian racing in general," she said.