Premier Campbell Newman says he has accepted her resignation with regret.
Mr Newman says she told him she had felt under a lot of pressure.
"I think it's affected her health and her recovery from a serious illness last year," he said.
"Her family have particularly suffered as well and that's the reason that she is going."
Mr Newman paid tribute to Ms Bates and the contribution she made to the portfolio.
"Ros has done an outstanding job under difficult circumstances," Mr Newman said.
"Unfortunately the demanding role has taken a toll personally and on her health, and she had decided not to risk those issues impacting on the performance of her duties.
"She has done the right thing by her family, her constituents, and the government."
Her resignation comes after months of pressure over her contact with lobbyists.
As recently as this week, she has been the target of Opposition attacks on the issue.
The Opposition had alleged that Ms Bates deliberately misled the House when she explained why a lobbyist contact register had contained errors.
However earlier this week, Parliamentary Speaker Fiona Simpson ruled out referring the claims against Ms Bates to the Ethics Committee.
Late last year, Ms Bates took extended leave while recovering from shoulder surgery and after injuring her back falling down stairs.
Ms Bates had also been facing questions about her son's job with the Government.
She returned to work in early January.